You can choose from literally hundreds of car seats when purchasing a vehicle, and I have never, ONCE been in a car seat less comfortable than the standard airline economy seats which, despite coming from different manufacturers across different airlines, are universally terrible. Flat as a board so you put pressure on your tailbone, no support anywhere, just terrible. I'd rather sit on a park bench.

Give me the option of paying $200 per ticket to sit in my car's seats on an airplane, I'd do it every time.