@Dave ********
that is a great question! And I'm sorry I have to ask... Do you think this represents their only profit?
Look, there is a difference between "not leaving money on the table" and "making shit up because you think you can get away with it. It isn't even semi justifiable like "want to pay 3 dollars for an email about your flight" or "20 dollars for seat selection and then EVERY seat is a charge beyond that". They are charging 20% or whatever extra to bully you into signing up for a thing where they will charge you 100% of the ticket price every month" and hoping you don't notice.