The whole point of Turing Machines is to eliminate all of these different kinds of uncertainty. There is in point of actual physical fact no such thing as a Turing Machine. Digital computers are really analog under the hood, but they are constructed in such a way that their behavior corresponds to a deterministic model with extremely high fidelity. It turns out that this deterministic behavior can in turn be tweaked to correspond to the behavior of a wide range of real physical systems. Indeed, there is only one known exception: individual quantum measurements, which are non-deterministic at a very deep fundamental level. And that in turn also turns out to be useful in its own way, which is why quantum computing is a thing.

Right, the point is that we don't need a solution to the 'measurement problem' to have a quantum computer.

Well, yeah, obviously. But my point is that you do need a solution to the measurement problem in order to model measurements in any way other than simply punting and introducing randomness as a postulate.

And is that solution required to be deterministic? If so, that is another postulate.

You have to either postulate randomness or describe how it arises from determinism. I don't see any other logical possibility.

BTW, see this:

https://arxiv.org/abs/quant-ph/9906015

for a valiant effort to extract randomness from determinism, and this:

https://blog.rongarret.info/2019/07/the-trouble-with-many-wo...

for my critique.