(nods) Makes sense.

Presumably the reason you have such confidence about the interchangeability of identical chips is because your experience encompasses lots of examples of such chips behaving interchangeably to support a given application. More generally, you've learned the lesson through experience that while two instances of the same product coming off similar assembly lines may not be 100% identical, they are reliably close enough along the dimensions we care about to be interchangeable.

And, lacking such experience about hardware/wetware interchangeability, you are properly less certain about the corresponding conclusion.

Presumably, if that sort of experience became commonplace, your confidence would increase.