No, it's not. I was a cashier for years. I was not doing any service for anyone. I was taking money from the customer and literally nothing else. The service I provided was for the store, not for the customer.

a server at a restaurant takes your order, chats you up, and brings your food from the kitchen/bar to your table. You are on your feet, moving around, putting on a show for people. that's a lot more work than what I did. I never wanted to be a server because it I would hate to have to work so much, even if I made more money.

Hell, in Europe cashiers sit down on the job the entire shift.