Please exactly define your term of "normal world".
I did. Re-read my post and pay attention.
We're talking about
PE so a "normal" world in that context is one whose GWP produces enough RUs to make it relevant. The Resource factor rarely very exceeds 20 and the Infrastructure factor cannot exceed tech level. That leaves it up to the Labor factor to "create" the large GWPs needed for significant RUs. However, while a large Labor factor is needed to create large GWPs, a Labor factor below a specific point cripples a GWP.
The Labor factor is a product of the population multiplier and the Labor Base adjustment. The adjustment is the key and it increases by orders of magnitude just as population does. That adjustment doesn't reach a "neutral" value of 1 until a world's population code is 8. Look at a few worlds, each with the same Resource and Infrastructure factors, each with the same population multiplier, and each with different populations. We'll use Resources 15, Infrastructure 12, and a pop multiplier of 5.
Pop code 6 => Labor Code 5 => Labor Base 0.01
Pop code 7 => Labor Code 6 => Labor Base 0.1
Pop code 8 => Labor Code 7 => Labor Base 1
Pop code 9 => Labor Code 8 => Labor Base 10
[15 * (5 * 0.01) * 12) = 9
[15 * (5 * 0.1) * 12) = 90
[15 * (5 * 1) * 12) = 900
[15 * (5 * 10) * 12) = 9000
While those raw scores still need to be adjusted by Culture scores, trade volumes, and other factors, the power of the order of magnitude steps should be apparent. Below a pop code of 8, a world doesn't count for much. They won't be producing the RUs your pocket empire needs for investment, advancement, military forces, and everything else. Such worlds will be hard pressed just to pay their own bills.
You've only read through the rules, you haven't actually played
PE. Because you haven't sat down and run through a century's worth of yearly budgets trying to improve starports, advance tech levels, build infrastructure, tweak cultures, create military forces, and all the rest you don't quite grasp the power of population in creating the RUs of which you'll never have enough.
The "order of magnitude" stepping used is another aspect you don't quite grasp. Population code increases become harder and thus more rare as population codes increase because the "distance" between the "steps" become larger. Shoveling robots into the mix doesn't work either because of the number of robots required to reach the next order of magnitude. To increase a population of 10 to 100, you only need 90 robots. To increase a population of 10 million to 100 million - which gives us that magic Labor Base of 1 - you need
90,000,000 million robots. Robots can only plausibly increase population codes for those codes small enough
not to matter.
Shifting robots does not work from either a design or mathematical standpoint.
PE contains two sample campaigns; The Empire of Seven Stars and the Cararialta Family. The latter is an exercise in long term frustration because of the RU totals involved. The Cararialta's and their nascent empire are extremely poor in the game's terms. You have to spend centuries slowly building before you have budgets you can do anything with. The Seven Stars campaign is a much better one in which to not only learn the rules but to also see how the rules play out in practice. Do yourself a favor and play 50 yearly turns of the Seven Stars campaign. It will be an eye opener.