>I look at it a little differently. The urban cores in the USA are actively hostile places for anyone to be. You step outside your door...into an empty hallway of doors. You take an elevator or stairs down to a place with a few mailboxes, then step outside.

I'm sure such places exist, but I've lived in a city (Boston) for many years and this description doesn't apply to the areas I've lived.

Somewhat ironically, the places in Boston that are closest to your description are the ones where they bulldozed large swaths and tried to remake things in a more people friendly way.