What I'm calling "sucker tax" is only the difference between the actual price versus the "eyeballed" price of something inside one's head, because the person didn't bother to run the maths. This is an actual thing when fake currencies are involved.

For example. A platinum award should cost 4~7 dollars. If we told this to two different users, who just gave someone a platinum award:

• Alice: "wow, that's too expensive. I'm not giving awards any more."
• Bob: "I know, I'm fine with this."

Alice is paying the sucker tax; Bob isn't. Bob's case is a lot more like your cheeseburger example.

This is relevant here because the sucker tax usually requires some in-game "fake" currency, like Reddit coins, to mask the real cost of the action. It's a piece of user-hostile design that you see often in games full of microtransactions.