Upselling has pretty much always been around. When I worked at Taco Bell 25 years ago they still required us to ask if they wanted Cinnamon Crispas with that (not Twists you lazy fucks, we had Crispas!), or an extra taco, etc.
I pretty much just say "No, thank you" and brush it aside, because I know they fucking hate it too. The only way we'd ever come close to getting rid of it was if every time it happened we called corporate and complained, or filled out the complaint card, etc. We all know that the employees would love more than anything not to have to do it, so I don't blame them.
Hell, my dad used to be a real prick when I was a kid and he'd get a Quarter Pounder, and they'd ask if he wanted cheese, every time he'd reply, "If I wanted cheese, I'd have said so." When I finally worked fast food I explained how it was and told him to lay off. His jimmies were certainly rustled until then.