There's probably a lot of infrastructure work that would have to be done for that to be practical for a lot of people. I'm lucky that where I live in Australia I can actually do quite a few trips without the car (I would quite like an electric bike with some cargo storage to be able to do more, but I haven't made the fairly big investment yet), but the situation in a lot of places in the US (especially suburbia there) seems like to get a lot of places, walking and cycling can be quite dangerous or inconvenient.

Improving this definitely should be a priority for cities though, on so many points (climate, reducing pollution, improving health from the exercise, reducing car traffic by moving trips to other modes, reducing car noise, etc. etc.)