At least in LA transit was never really removed. The streetcar system evolved into a bus network that is far more comprehensive today than the streetcar system ever was. What changed was really income levels. Already by the 1920s streetcar systems were in decline as the used car market started kicking into gear and making a direct transport option affordable to most all working people. To this day it is still highly affordable to have a car. There are used car lots advertising $0 down $50/mo financing with merely holding a job at all being enough to qualify for that financing. "Tu trabajo es tu credito" painted on the walls.

Other places you see more transit use usually come with significant cost barriers to driving for most of the working population. In nyc this includes bridge tolls and paying for parking.