your lack of economic training is why you don't see it, and you've just laid it out perfect. One of the problems in the shift from micro-macro analysis is that of the scaling problem. An entire month is devoted to the scaling problem in economics 202. For example, one you see in education is Finnish schools have better results, if we adopt the Finnish school system we'll have great results, let's adopt the Finnish school system. the problem fails to account that when you shift a problem from a small, homogenous society with a particular welfare system and environment, to a transcontinental one, other variables in the equal change. Similar with "pilot programs" in industries, whether the post office or UBI or pizza delivery. So, while a mask may prevent an exposure from one person to another (in say a dummy test or in a supermarket exchange) when you scale it up to a population level it won't work as well because errors and other variable begin to creep in. The one you most often overlooked (which you yourself admitted) is that masks don't prevent anything in home transmissions, which is the biggest source of transmission. Another one is work: while 2 people wearing a mask may prevent spread in a quick exchange with a supermarket cashier, it's not going to stop the fast food worker working hours on end next to another co-worker (and we KNOW this from mask studies done early on by the German health authorities in their meat process plants and car manufacturing factories). Other errors creep in too: people don't wear masks properly especially over long periods of time, people are sick so they think going out with a mask is o.k. because others are protected, germs build up on masks, masks get worn down in the wash. So if your dummies show a 10% potential change in transmission, that's not going to scale up to 10% change in the overall population or to R.
What's truly astounding is that your faith is blinding you to the fact that you've pointed out yourself exactly the reason why masks are failing on a macro basis all over the world (and we've seen this very clearly now whether the Texas county mask study, or comparing England and Scotland or comparing Los Angeles and Orange County)....masks, particularly with the Delta, have made very very little difference. I know you have to done anything and everything to preserve your sacred talisman. You cannot abide the possibility that you might actually be wrong and your talisman may actually not be that effective. But it is the sad reality of things. And that fact that you YOURSELF have shown this, and can't see it, would be really quite funny, if it wasn't so sad.