On the other hand, given that some worlds in the Traveller setting are definitely overpopulated, and others are headed there, I'd say one of the likely things for conscription would be colonization and expansion of territory by various space fairing polities. Build a basic ship, pack it with your excess population, and send it off to system X that has had just the most basic survey done to know that there's a planet there they can survive on. Wash, rinse, repeat, until the excess population is no more.
Here, you--the government--doesn't have to particularly care if the "colonists" are suitable for this purpose or not. They're surplus to the government's needs and the cheapest way to get rid of them in some useful fashion is to ship them off to some god forsaken, unclaimed, system to colonize it. You could send criminals, religious zealots, revolutionaries, the disgruntled, persons that don't measure up in terms of productivity or intellect, etc., to do this. They succeed, great! They fail, send another ship load and try again.