It's not even that they're built for cars. They're simply just not built for humans to walk around.

If you've ever been in a situation where you're visiting a friend in an unfamiliar neighborhood and the map is telling you that your destination is physically just "right behind this house", a mere 50m away, but the front street you're currently in is a long crescent without cross access to the back street where you're trying to get to, you've experienced the frustration of modern planning with no afterthought for human access.

I'm no expert, but I've done my fair share of traveling. One thing that's always been very noticeable to me is the strong correlation between highly cohesive communities and the many seemingly disorderly pedestrian paths crisscrossing their neighborhoods.