Cryogenic transport modules provide the same income as luxury passenger accomodation modules by giving the luxury passengers 40 times the income per person. If you put both on the same ship however, this bonus is being applied to all the colonists on the ship, not just those in the luxury modules. When you couple that with the civilians being able to build a ship of any size as long as they can afford it, you get ships that generate rediculous amounts of income.
