well that lack of info is mutual.Also consider, that Traveller does have stealth -- practically perfect stealth. It's called a Jump drive. Using a Jump drive, a ship can achieve strategic, and, possibly, tactical surprise, as they just appear out of nowhere. What they can't do is gather intelligence and lie in wait. When they arrive, they arrive blind.
That is not entirely correct. The in-jumping ship will be able to observe the tactical situation as it was so-and-so-many light-seconds/minutes/hours ago from previously emitted/reflected EM-radiation, but the ships already in-system will be entirely unaware of the in-jumping ship's presence for the same amount of time.
So the in-jumping ship(s) will have a space of time for free action before the in-system ship(s) become aware of its presence.