Okay, Polly–I mean, Five :), I bow to your experience.
I’m not saying all managers are jerks, and it’s nice that you’ve come out of your work experience with such a kind impression toward them. However, I can just see the expression on a manager’s face if a pimply-faced new hire said, “Pardon me, but I’d prefer ‘Mr. Doe’ to John. Please remake my nametag.” The respose would probably be, “But everyone has their first name. I’m not going to make an exception for you. The corporate office would ask what the hell is going on.” Plus, Mr. Doe would get the reputation of being a trouble-maker from the get-go.
However, given the universality of first names on nametags, not only in food service but in retail and many other areas, I concede that it would be odd to carefully avoid calling any service person by their first name. I don’t think it’s oppressive–just a bit overly-familiar when “sir” or “ma’am” would do.