Nothing in gran turismo is behind the paywall. Everything is free. If there wasn't microtransaction everyone will be force to pay for season passes and dlc.
Go try iracing or assetto corsa.
Then come back with you fake outrage
assetto corsa has expansion packs and most of the time you can get the game and every DLC for less than 50€/$ (buying everything at launch it could probably have cost you around 150, maybe 200€/$)
iracing is expensive (subscription + you pay for tracks and cars) but you don't pay 40$ for a car (you pay 10$). but it is a system that almost encourages people to specialize on certain categories, so you are not constantly buying new cars (tracks yeah, if you want to race everything you have to buy a good number of them). But again it is seen as a simracers hobby, not as a videogame. (it seems stupid, but there is a difference).
EDIT: just to add the difference between gaming and "simracing hobby"; simracers could easili spend 2000$ dollars just on a simrig (without considering PC and monitor(s)), so spending the 10 dollars here and there for subscription or a new car/track doesn't even register.
VERY DIFFERENT from the guy who just got the new GT game for their playstation.