I can think of several reasons NOT to have starports everywhere, among other things the flight patterns of the kind of tonnages you are envisioning would make the sky dark with starships coming and going, whether booming in on a multimach reentry or whispering in grav drive, that is a LOT of tonnage in flight that many people may not want directly landing, but would be happy with planetary grav/nautical delivery.).
Given the air traffic currently controlled, Id say it is quite manageable. O,Hare (Chicago) alone processed June 2015 76,026 flights with 7,012,037 passengers (their site stats)
IOther arguments include limiting extrality and/or 'off-world influence', desirable real estate, pollution/noise control (a big one in my ecodisaster theme of Earth, Mars and Alpha Centauri, everything HAS to have grav drive to be allowed to land), customs enforcement, plague/biohazard risk limitation, and general fussy high law level control issues.).
You enter the realm of Starport's Mission, and I agree that this non UWP parameter is likely a dominant one. It is also the potential source of role playing and explanation for odd things.
As to quarantine, custom, extrality transit zone, etc, if all inbound Starships are processed at the Highport's Orbital Roadstead Anchorage, there are few remaining dirtside issue, except the usual ones involved with local air traffic (see above) and one or two dirtside extrality zone. Again, DS9 style Highport is a great role playing venue.
Which is not to say no big pop planet should have more then one starport, merely that some will have many and some will not, and it should not be forced one way or another to allow for different flavors of enviornment and adventure/trade challenges. ).
Indeed
Could be the interstellar polity has a universal law saying there is one 'port of entry' into space beyond 10D for member planets. That's again IMTU territory. ).
Universal law... pushing too hard. Of course, it is quite possible, even reasonnable for a polity to have that rule. On a planet with a small settlement, that is one port. On a large planet with large pop, that function is best taken care of by an "orbital hub" high port
Kind of skipping over the part where the ships had to be rigged that way along with their containers, and that the world moved on from that system apart from military sealift.
Which is what operating a huge tonnage through an E starport would be, a barren rock military basing type 'spacehead' specialized ships with a starLASH system built in picking up and dropping things off with their own integral cargo handling either in the container or the ship design.
Costly in specialized equipment and time compared to commercial operations, trying to do a Long Beach/LA container type setup in a Somalian harbor, especially with financing and building ships for such a trade without variable fees covering the greater costs in having ships that lose profitable tonnage for a specific planetary trade's non-existent facilities.
Right, old Lord Rethe made the same calculation when he wanted to be a nuisance. It just happen that the "filty rich" have the money to pay the high cost of inefficient practices. Remember, a E class starport in a A pop is an odity that require retcon or some creativity.
I really don't care about the distinction of public vs. private starports. You have a private starport that is effectively B or C and everyone does business through there, then in my book the UWP gets a B or C rating with an asterisk saying 'private, normal fees and public rules do not apply'. Most mercantile lines are not going to make special investments in rough field operations unless the profit in bypassing the private starport is worth it. .
Wish the UWP would be that sophisticated.... see the arguments as to the meaning of X
While waiting for T6, you are free to presume a free market economic making pop A Straport E possible. Again, my explaination (I do not pretend it is the universal one, just mine for Rethe, Hans as another of more general application) the Cartel Members are not allowing non member in their private spaceport "I make more money carrying the cargo your ship would carry than I do repairing it and allowing you to compete with me on freight". They corrupted old lord Rethe to make sure the administration would not allow a full service starport for every commer. Other explaination linked to planetary politic tampering with free trade are doubtless possible.
Adventurers however have exactly that kind of craft and they have the time to pick up extra business. But again, 1000 Free Traders landing a day without traffic control?
For the kind of tonnages you are throwing around, you darn well need big cheap open structure 10-100,000 ton super freighters hauling in that kind of load, which yes requires a highport. But even if we are talking dumping and going, it's sheer madness to think a Berlin Starlift operation is going to work without traffic control.
E starport. NO facilities. No tower.
I don't know what part of no facilities means some facilities. Your IMTU interpretation of making a scenario work, not the rule and not sole justification for defining high volume wherever big pop is no matter what.
Who says no traffic control?
E. Frontier Starport. With no facilities, the installation
is little more than a flat expanse of bedrock and a sign. This
designation effectively means there is no starport, but there
have been previous landings and that location is indicated in
astrogation records. (T5.9 p.267)
in the incremental progression toward D, there is a point where some component of that D get put up at the known location (basic requirement for E: beadrock, beacon at known location, see table p 268), then some more get put up, then there is a point where all you need to be D, and maybe some of what you need to get C, are up and running and you get the D grade by the classification powers.
And yes it is why that trade is likely going on with large ships
I just don't buy this need to make sure there are millions of tons going to a pop A world that is being strangled by a power weasel as justification for changing the whole trade system or what a starport means.
You also seem to be ignoring the crowded skies aspect of this sort of tonnage as standard, or what that practically means in terms of how many ships are coming and going. It sure isn't CT encounter levels, and it won't be CT sized ships either, a LOT of big boats to make that happen.
Is that the environmental effect you want on gameplay? I don't, but if you do well then more power to you. It just should be consistent if you are going to the trouble of defining millions of tons per week (and many more for a well off planet).
You are right, this is no CT encounter level, it is posted in T5 for a reason.
I do not need millions of tons to move about, I need to be logical and it is logical that High Pop world would get that kind of volume for reasons demonstrated.
Crowded sky was treated above
I am not changing the trade system, I cannot because there is no macro economic trade system defined in T5 that I could change. I try to figure a system that make some sense for background purpose given what we know (including new ships' design rules). I asked who think high volume, who for low volume? I register your vote for low, thanks. I believe both coexist given the circumstances. I can't see a UWP based magic formula emerging yet from this interesting discussion.
As to the gaming explanation, I could just shrug Rethe as a UWP missroll. I took up the creative challenge, knowing that nothing I say is canonical but trying to test my ideas against whatever we know of the OTU.
As to consistency, I am glad to see that we are many trying to figure a system that acheives it. Adventure Class Economic tables are explicitly ruled out as general tables. It does not mean that interstellar trade must be high, just that we are on our own to figure it.
have fun
Selandia