[acollins1331]

It's pretty simple at face value. You're interacting with a person instead of a screen, that's basically like a game where you try to "win" by getting the best price for all the stuff you're ordering. Of course you might know it's wrong but you don't see anyone (and can likely assume) no one directly involved will take the fall for it. Compared to a cashier that gives away something for free, they might get yelled at or lose their job. It's empathy, it's human, and it makes a lot of sense.