Who needs tastebuds?

Faithful readers of this blog will recall that I have long struggled with a diet soda addiction. Fortunately I've been able to replace most of my soda consumption with coffee. At least at home. When I'm out, I default to pop, mostly because of the temperature. Every time I have coffee (non-iced) from a shop or restaurant I experience severe tongue damage. Yet I see people get a steaming cup from Starbucks and immediately sip all the time. Have these people so damaged their tongues that they are desensitized? Or do have a particularly sensitive tongue? I really would love it if someone could explain this to me.