Quote - Re; rights: I don't have a right to buy stamps at the post office, but when I walk in and ask for some, I expect to get served.

 

In the US, at least, the Post Office can't refuse to sell you stamps, at least as long as you aren't breaking the law while in the Post Office. (And they are open, and they haven't run out of stamps, and you have a way of paying for them etc.)