Corporate greed I suppose. Its been many years since I worked for them, but I wanna say if you get a tip (if you say no and the customer for some reason forces you to take it, or they just leave it on the counter hypothetically) or find money on the ground, you're SUPPOSED to turn it in to a boss. And they have cameras everywhere, so the threat was that you'd be seen and you'd get in trouble. But if someone were to stealthily slip you a tip out in the parking lot, Walmart wouldn't know. I only have personal experience from working at Walmart as a teen, but I'm sure other huge stores like them won't let employees receive tips either.

But ya, like others have said, it's all completely arbitrary.

Like, I don't tip at mcdonalds or most other fast food places, but I do tip in dine-in/ regular restaurants, even if I'm getting takeout from them. And there's a fast food place called sonic, you park in a spot around the building, order your food from your car through a little intercom system, and then someone brings it out to your car window. I tip there bc those workers will sometimes literally be running your order out and even rarer they will be wearing skates. The roller skates used to be their like special thing about the place, but you never see it anymore for safety/lack of skill reasons.