I know less than nothing about kashrus but to my ignorant eyes it seems that people in this topic are piling chumras on top of chumras and wondering why other people aren’t keeping them.
IIRC, a strong case can be made that dishwashers cannot become milchig, fleishig or treif. The same goes for microwaves (although for different reasons, I’m sure). Now, when we have a store that has some treif keilim we are mechuyav to assume that all the keilim are treif because they may have been washed together? When a store with Kashrus supervision makes one little mistake, with a microwave, which is arguably not a problem at all, and they lose their hechsher as a result – people say that they wouldn’t eat in Dunkin Donuts with a hechsher.
Same idea for cholov yisrael. Is there a source for the idea that we need to suspect that someone switched it? There is a halacha about wine, and there is a halacha about meat, when they’ve been left open with no supervision. But both of those are assur gamur if they were switched and there is a significant motivation to switch since they’re expensive and the price difference is drastic. In the case of milk it’s at worst switched for chalav stam, the price is cheap and the difference insubtantial. Does it follow that there is necessarily an issue to drink milk that’s been left unsupervised?