As with seat belts, whether people use masks properly matters, but no randomized trial could conclude seat belts “don’t work.” At best, that type of trial would be a truly inefficient way to assess specific instructions and incentives to get people to use them properly.
Being someone who wears a mask is pretty lonely these days. Sure, they are annoying but I am certain they work.
I know lots of people seem to think they don’t work because they aren’t effective when worn incorrectly. Those people are idiots.