[MichaelGroves]

> Depending on the person and the prevailing culture it may be perfectly normal to more or less ignore someone outside the office

Precisely this. When about town in public, I ignore everybody except my closest friends or family, or people I have arranged ahead of time to meet up with. For me, this is an application of the Golden Rule. I do not like it when work acquaintances approach me in public and start trying to idly chat me. I don't like it when that's done to me, so I don't do it to others.

Hearing that some people will interpret this as racism or similar is disappointing and disconcerting, but I'm not going to change my behavior. If somebody is making those assumptions, that is disappointing but their assumptions are their responsibility, not mine. And frankly, treating others as I wish to be treated takes precedence over treating others as they wish to be treated.