We know that Extended Church-Turing Thesis (or Cobham's thesis) states that any 'reasonable' model of computation can be equivalent to Turing Machine model in at most polynomial time overhead.
People always believe that this ECTT is not true and a candidate counterexample is quantum computation. But, why they don't see Nondeterministic Turing machine as a counterexample? Is it because it didn't correspond to any real-world computing device?
Note: I don't know what is good tag for this question, so if you know one, please let me know.