What if I can't fit in a shoebox and can't afford anything larger? What if I have a dog and want them to have a yard that doesn't require me to leash them every time they want to go outside? I don't mind sharing a yard with neighbors, heck I would even share a kitchen space if I knew it would be maintained well and available when I need it. But none of that is even an option.

I don't buy the idea that only hyper-dense cities can be walkable. The fact that NYC, Boston, Chicago, etc. are the closest thing we have to anti-car living speaks directly to OP's point about the US not prioritizing building comfortable communities.