I live in Scandinavia, in one of these walkable cities.
Everyone has a car. Why? Because relying on public transport or walking/biking everywhere is not practical. It's just reality.
That's fair enough. I also own a car, but I try to use alternative means of transport (bus, bike, walk, skateboard) whenever possible. It's the prioritisation of cars over all other modes of transport where I have the issue. My city is riddled with car filled streets criss-crossing all over. There's a plan to take one of the most shop focused streets and make it walkable. It would mean that I would be able to get to work almost the whole way on it. I hope it goes through
I'm not disagreeing with you or most people here for being annoyed by everything being build around car usage.
I just don't see it realistically change. You'd have to rebuild most cities from the ground up and invest ungodly amounts of money into several modes of public transport in every city. It just won't happen.
I've had to use public transport to get to a job I loved in a neighbouring city, due to not having a car at that point. Where a drive with the car would have taken me about 20 minutes one way, the bus+train combo I was forced to use was 1,5 hours including waiting times. It was so draining that I quit that job after 6 months.
If this is the choice you need to make, people will take that car every time because you can't rely on jobs being available within 20 minutes of walking or public transport, most cities aren't build to offer jobs+housing+shopping within a small radius for all the people living there.
The part about going to your job is totally valid. Some jobs can be worked remotely or partly remotely now, but that doesn't apply to all professions, so that is something to keep in mind.
In terms of not being able to realistically change the current cities, many of the best walkable cities prioritized cars first and then changed. It took decades, but they eventually achieved it.
There's this presentation I found after doing some research on the 15-minute cities conspiracy theory, and it was a really interesting talk about how towns and cities can be changed into slower, more accessible ones. It's an hour long but there's a 5 minute segment where it discusses cases where cities have changed from car-based to a more walkable one, in this case Amsterdam and Pontevedra (in Spain).
I recommend checking it out. Here's a link with the timestamp of the start of the section about those cities:
In the section before this one, he discusses the cost of other transport modes versus cars. Building and maintaining infrastructure for cars is waaaaay more expensive than for other methods, so cost isn't an issue. I've included the slide below.