The other US phenomenon is mega-chains which can operate at much narrower margins (or even negative margins in some marquee locations).

To be fair, that specifically is not a US phenomena. Flagship stores that operate as a loss purely for the prestige of a location have existed basically since the dawn of modern retail. Operating in Manhattan or on the Champs Elysees is a sign you are a serious grownup store.

The flagship stores yes, but that was the special case (which is universal) of the more US-specific case of e.g. "why the fuck are there Chipotles everywhere"

Oh i see. Yeah, the corporate structure of “landowners with a business attached” is somewhat uniquely dominant in America. Though not totally unheard of, Japanese rail companies are property developers for example with attached department store chains, etc. so that trains and property drive foot traffic to each other.