Depends on whether I think the restaurant pays the person living wages or not. Most restaurants have bartenders or wait staff giving you takeout. They are doing almost the exact same thing they would do if you sat down, except not pestering you a couple of times. They bring you food and drinks you order, wrap "leftovers" in a container, etc. Really the only thing they aren't doing is walking back and forth to where you are sitting. What exactly are you supposing that a waitress/waiter does when you sit down vs when you get takeout? The only thing is the actual act of waiting for you (as in, I'm waiting 15 minutes then coming back). Why does that deserve 15% but doing everything else involved in serving you except waiting around for you doesn't deserve any tip at all? Is your theory that a waitress earns all 15% by virtue of the fact that you are sitting at a table and the person interacts with you twice more to get the same effect?