They don't work and increase the chance of infection. Scientific studies showed that. Go check them on /s/coronavirus
Maybe there is an alternative that does work, like a face shield.

Another fact is that we are near herd immunity in most places. It is like wearing a condom at the baby-shower.
Also only a small % will get sick.

It would be better to identify the weak and keep them shielded with proper measures, even financial support. We can also help them with HCQ , that prevents covid-19 according to doctors.
But that is less "profitable", now the elite can buy huge properties for very cheap,
and sell non working medicine (Remdesivir/ Vaccine).