I lived in a city with extensive public transportation infrastructure (Moscow) for 7 years without a car. TBH, I would not trade my current suburban US lifestyle for a high density city. Want groceries? Gotta carry them in all the way from the store (which usually within walking distance, but still, shit's heavy unless you buy groceries every day, which can be quite wasteful). Job not within walking distance (which it rarely is)? Say hello to 1-2hrs of daily commute (about 35 min of which for me was walking). Kid has hobbies that aren't within walking distance? Pain. Need to get something from a store that's not nearby (i.e. hardware, household goods)? Long commute _and_ carry stuff as well. Need to get something you can't carry? Gotta rent a car or pay for delivery. It's snowing or raining? Tough luck, gotta walk to the subway and/or store all the same. Etc, etc. Hundreds of these situations where in the US I just get into a car and go wherever I want. I don't even get wet if it's raining outside.
This "car-less" stuff only looks good (on paper) to two categories of people:
1. Europeans who never had a car and therefore don't fully understand the upsides
2. Americans who never lived without a car and therefore don't fully understand the downsides