I agree with the OP's sentiment that cars are mostly not needed. We've just been hoodwinked into building in car-friendly ways instead of people-friendly ways, and so we have these spread-out, fragile, suburban areas that depend entirely on cheap oil to function (if not the gas itself, the manufacturing, maintenance, and support of cars and car infrastructure).

Instead of building too dense (skyscrapers - opposite end of the problem spectrum) or not dense enough (suburbs) we could have built mixed-use walkable neighborhoods and towns and really reduced the need to spend money on cars. But hey, Ford, GM, and Chrysler had great lobbyists back in the day, and the threat of nuclear war with the Soviets meant that getting tanks and troops from one place to another necessitated the construction of extensive highway and freeway infrastructure. Win-win for a segment of the population with specific beliefs. Now we're so used to it that we find it hard to imagine living without it.

It infuriates me whenever I talk to people and they're like "wow Europe is so walkable! You can just go to the cafe down the street." or somewhere like Mackinac Island (aside from the horse poo) where people go to vacation - it's like yea we could just build like that everywhere if we wanted to. But we're dumb and we don't think and construction and automotive jobs need subsidies to keep the economy growing.