No, these are not public policy studies. These are medical studies. Do they measure the effectiveness of an experimental medication on people who stop taking it? No. If I were to measure things as you propose, I guarantee you I could conduct a huge study showing that exercise doesn't make people healthier, just because most people won't adhere to an exercise program. That has no bearing on the effectiveness of the intervention.

The point of these studies is to show people that the intervention works if people do it. And, yes, there are public policy studies showing that mask mandates don't work, but that doesn't mean they don't work for the people actually wearing them. It just means people who refuse are cutting their noses off to spite their faces. As noted in another comment, this isn't the beginning of the Third Reich, and should not be controversial at all.

All drug studies are public policy studies.

If you show that a drug works in a petri dish, that's completely irrelevant if it's so toxic that people don't take it because of side-effects.

If you show that full-face respirators work on a mannequin in a box, that's completely irrelevant if real-world people don't wear full-face respirators because they suck.

> If you show that a drug works in a petri dish, that's completely irrelevant if it's so toxic that people don't take it.

> If you show that full-face respirators work on a mannequin in a box, that's completely irrelevant if real-world people don't wear full-face respirators because they suck.

And these examples are straw men. That's completely irrelevant to the point.