I grew up around a lot of Indian people, and I have definitely had the curiosity to know how to ask, but at the same time known that it would be taboo. I can only guess from their wealth or their last names.
Chipotle and Starbucks do it with online orders. However, they do that because they are big enough corporations to replace anything wrongly taken for free.
This really varies a lot with where you live. I'm almost an hour out of philly, very solidly middle-class office-y medical/pharma area and yeah, the sushi place I go to (not a chain, local place) just lays out the stuff on the counter for pickup, and you just look at the attached receipt since you actually what _you_ ordered. This would of course be ludicrous to do in some parts of the city itself.
