But don't leave time for a response! Hand the paper over as you drop a one-liner (“would love to grab coffee sometime!”) on your way out.

Note to others:

A small fraction of the population will still have their days ruined even by such an unintrusive approach, but to ensure we never bother a single soul we’d need never to interact with anybody. We certainly have to be VERY careful with captive audiences which is why end-of-transaction + departure approaches are a necessity, whereas there’s no such mandate in a nightclub: they’ll have to deal with it if you offer to buy them a drink and, after declining, they still see you on the dance floor later.

You don’t want to absolutely restrict humanity from basic social interactions, and you don’t want to force humanity to offer a social response when they can’t leave from somewhere they’re being paid to be (with pressure to offer good service/be pleasant). There is a happy middle ground.