Steve Foley writes:

I'm curious to know how you have determined what 'most private pilots know'.

Private pilots are no different from the average person when it comes to
higher mathematics, physics, and gas theory, and the average person doesn't
know much of anything about these things. Therefore most pilots don't know
much of anything about these things, either. Simple logic.

I suspect you don't even know a significant sample.

Not necessary. See above.