All we want is to be teated as normal people.
i think this sentence can be writen like this:
All that we want is to be teated as normal people.
And the word"all" is a special collective noun which is singular indeed just opposed to its surface implication, and we usually omit the word "that" behind it for simple, but if we add it "that",then it's obviously to see that the verb should be IS not ARE since "that" is singular!
I hope I made myself clear! :p