[Delk]

You probably mean probabilistic Turing machines. Non-deterministic automata in general don't involve randomness, and the results of their computation are considered to be deterministic despite the name.

And of course all TMs are just theoretical models. Non-deterministic Turing machine equivalents in particular don't physically exist and may be physically impossible.

But of course if there is indeed true randomness in nature that needs to be modelled, that same randomness can be used a source of true randomness for computation, and you can then build computation that does have stochastically determined results.