We are only 'pretty sure' of the mechanism of how Tylenol works biochemically as of 2025.
You can test for effectiveness and dangers and everything else you need to prescribe something to get a good idea of whether its actually doing something or not.
'Alternative medicine' is largely, "I felt better after a bit".
They don't have the literacy / abstract thinking necessary to understand themes and like the 'vibes' of nerdy things being cool now.