I am puzzled about that too, as it seems far more restrictive than what is currently done in most countries, and that cannot be the intent of a MIP.
I am a layman, and maybe I’m being ‘too creative‘, but here’s an idea:
AFAIUI, the MIP defines two types of checks. An ‘operational’ and a ‘functional’ one. Operational means it needs to work (as in a light bulb works or not), functional means it needs to pass a number of quantitative parameters.
I’ve come to the same conclusion. As far as I can see this isn’t spelled out anywhere, but given how the terms “operational” and “functional” are used (in the new part-ML at least) that’s the only reasonable interpretation. E.g. part-ML says that you should do a “functional test of the pitot-static system;” and it makes much more sense to do such a test using test equipment. Also, the knowledge requirements for a part-66 license consistently refers to “functional tests”.