I would think more people would be going to high-TL worlds, but less freight would be going to high-tl worlds *shrugs*
But from the rules, I can't really tell which way it is supposed to go.
I would look at it slightly differently and say:
People go to where they have reason to go, and return back to home unless where they are going will be their new home.
If you're at any given world, and you have to take a voyage, what will be your reasons to take the voyage?
A) One way trip away from current world. Passenger needs to avoid the law, or perhaps make a new start on a different world (emmigration comes to mind).
B) Passenger needs to arrive at new world to take possession of a non-movable good, such as land inherited from a dead rich uncle.
C) Passenger is a travelling salesman who needs to go to target world, but return someday.
D) Passenger is a tourist, who wants to visit a world, but needs to return someday.
Now, a while back, I mentioned (Maybe at the TML, or perhaps GURPS TRAVELLER at the JTAS online, or perhaps even here) that it makes more sense financially speaking, to spend your terms in the Imperial military, and then find a lower tech world to settle down on where your retirement funds will last longer. Why? Because if the cost of the meal is the same relative to the TL - ie, a meal costs 2 credits whether on a TL 9 world using TL 9 currency, or on a TL 12 world using TL 12 currency, then using TL 12 currency to purchase a single 2 credit meal means that the real value of that meal is cheaper because TL 12 currency is worth more than TL 9 currency. If all "retirement" funds are disbursed at the highest TL currency value, then it is worth more at the lower tech worlds.
In any event, CT does not go into details such as immigration laws, etc - which is a detail that the GM's must provide. One thing is for sure. In American History, captains who were taking on passengers from Europe and other various places, were required to vet their passengers qualifications to see if they would or could qualify for immigration into the United States. At Ellis Island (and other entry points later on), immigrants were required to pass a physical or be turned away, at the ship captain's expense of returning them to their port of origin. Imagine if you will, being a ship's captain in a Traveller Universe, where a paying passenger wishes to leave the ship and exit beyond the territoriality line only to discover that they can't.
What are the laws involved there? Does the person have to reside within Star Town until such a time as they can be deported back to their home world? Who pays for the deportation? When a passenger runs out of funds at a star town, how do they get food and shelter? These are details that are not in the Traveller books, and require the GM to determine for their own game worlds (if they even bother with such circumstances).
Well, enough on that. Me? I think the TL modifiers for passengers should either be muted (made to have a lesser impact) or they should be done away with entirely. That's just an opinion however...