Well, I tip for takeout most of the time, because of being a waitress in the past and I just know that extra buck that means so little to me can make a big difference in how they feel about how things are going (in a small restaurant, anyway).
Also because there were
far too many people I waited on who ordered to go just to avoid being expected to tip-- then they'd sit at the counter and eat anyway!
Leaving their stuff for you to clean up when they were done, just like a regular customer-- the only difference being that they obviously figured, "What? I got takeout, I don't need to tip!" And I worked at a restaurant that had a lot of little extra things that didn't come with the food, but regulars liked to ask for-- special dressings, a thing of salsa, some soy sauce, a to go water cup, etc. Basically, they'd get all the service of a regular customer-- a water glass filled, a few trips back and forth to get them all the extras they wanted-- but all packed into the three minutes they were at the counter. So they'd make you hustle twice as fast to get them everything, and then act like you'd done nothing for them. I hated people like that...Grr.
Or the damn fool woman who needed all the extra stuff, and as fast as possible of course, and then oopsie! spilled a dressing bottle
allll over the counter and floor and
still didn't tip, because after all, the server doesn't do anything when you get take out! Oooh, how I despised that woman...<sigh> All right, I'll shaddup now...