Shameless self plug, but relevant: a few years ago I did a test of the association between spatial layout and community cohesion which came back positive for a number of network analysis measures on two different data sets.
My (non researched) opinion on this one is that most westerners find cars useful, hence car free development risks creating a district populated only by people who can't afford cars. Segregating people in that way that is going to cause other problems, it happened before in the uk when planners decided it was a great idea to knock down aging buildings and replace with tower blocks of cheap flats.
That said I do think we need to challenge our assumptions about the role cars play in society. It is assumed that highways are for cars primarily and this needs to be reined in somewhat.
Car free development might work in places where there is already a sizable wealthy demographic choosing to live car free e.g. London.
As to whole cities going car free, are there any? Not something I've looked into, would be interested to know.
Has nothing to do with wealth and everything with zoning laws. If there's mixed use, enough density to justify good public transport then cities without cars thrive (just like they did before cars were invented).
Your "observation" outs you as someone that spent most of his life in the US where most cities were designed around cars. US cities are awful, by the way.
Imagine this: a bunch of folks come to a completely unexploited continent, rape and pillage until they ran out of land and then proceeded to create one of the most unhealthy societies ever.
It's easy to be economically successful when there's tons of resources and nobody to share them with, the true measure of a society it's how most of their people live: without public healthcare, no welfare protections, lonely, stressed out, sicker than their european counterparts.
You're right that Euro style compact cities are better than urban sprawl, though plenty of people still own cars in them, and those who don't still benefit from the option of doing so should they choose. I'm not saying it can't work at all, I'm saying there is a risk of unintended consequences if you take that option away, and that risk should be considered/managed.
Your rant against the US, while it has some merits, is misdirected at me; I have lived in Europe all my life and cycled to work for around 20 years (alas no longer). Perhaps my post outs me as someone who grew up in a rural area in a country that invests poorly in public transport (1 bus per day to the village, how's that supposed to work for shopping?) and as an adult I have hobbies which require transporting equipment to remote locations (e.g. mountain biking, mountaineering, performing musician). I can't see myself enjoying the well being benefits those things bring me and my family without regular ability to drive a car to our door.
There are a number of cities of varying sizes which discourage or ban cars. Notable examples include Venice[1]. I haven't done much research on the topic, because I live in the United States and will likely need a car for the rest of my life. But the idea appeals to me. Intuitively, I think we'd be a lot happier without cars.
https://ij-healthgeographics.biomedcentral.com/articles/10.1...
tldr (refined and simplified with a few years hindsight): more walkable neighbourhoods = better