Based on this data I am seeing tens of millions of people who don't prefer where they live. It's illegal to build a walkable neighborhood in most of the country.
> It's illegal to build a walkable neighborhood
Big cities like NYC or Chicago are already walkable.
> in most of the country.
I am sure you can go build a walkable city in the middle of Nevada or Nebraska. Your problem is something else - nobody wants to go there yet so it is a bootstrapping problem. What you are essentially saying is "a lot of neighborhoods where the jobs are are controlled by NIMBYs and they are not letting us convert those to walkable areas"
People already live in their car-centric houses. Creating walkable cores means pitching folks who can park outside their favorite restaurant on walking from a parking lot. It's easier to sell the concept to new folks, who will live within walking or biking distance of the new core, than gaining buy-in from incumbents. That, in turn, creates the opposition we observe.
What laws make it illegal to have walkable neighborhoods in the US?
Depends how much space you’re dedicating to car parking. Once the grocery store has a giant parking lot it’s swallowed up a lot of land that could have been housing.
The more the store depends on car traffic the bigger the parking lot. The bigger the parking lot the less housing it’ll have in proximity, the longer everyone will have to walk. A successful walkable neighborhood has to balance allocated space with thought.
That is not a walkable neighborhood. When people are talking about this stuff they're talking about an actual defined concept:
https://www.walkscore.com/walkable-neighborhoods.shtml
A home next to a strip mall might be close to a grocery store, it is not a walkable neighborhood.