That’s not an apples to apples comparison. I am buying a single thing at a pump: fuel. I boop my card. I stick nozzle in hole. I pull lever until it stops. Vending machines? Second verse same as the first. I boop card. I push button. I take chippies, I walk away. Vending machines specifically are purpose-built for self-service.
I spend maybe 30 seconds to 3 minutes at these things. The only work I do is tapping my payment and pressing a button or two. Groceries are a whole different animal. It’s scanning, weighing, coding, bagging, loading, and paying. It’s a fuckton more involvement by the customer. I don’t think you can in good faith compare self-checkout to a vending machine.
The business is incentivized to trick you into performing labor for them. Part of the cost of my groceries is for someone to have a job doing that. If I’m gonna do that labor for the store, I should get an employee discount, at least.
This is a heck of a post to come across for me right now.