Because cars/parking still take up far to much space in dense city centers, making them more loud, dirty and dangerous than they would be without (most) cars.
No you’re right people rave about the car centric design of Los Angeles and it’s very efficient. Phoenix is a bastion of free movement and doesn’t demand everyone own a vehicle.
The public very much enjoys the convenience and speed of well funded public transit. Even if they don’t always enjoy the actual process if it isn’t well kept and clean.