All true, but: Clients in the salon can be limited to those being serviced at the time, others wait in their cars or outside until appointment time. Everything is swept, sprayed down and sanitized in between clients. Service providers and clients wear masks at all times.
The masks may help...depends on the mask and how they're worn.
https://www.prevention.com/health/a30677242/can-face-mask-prevent-coronavirus/
Part of the problem is the close proximity between the worker and the client. When you're that close, a cloth mask is pretty flimsy. Plus wouldn't the mask itself interfere with the haircut? Typically they ask clients to remove glasses. Full disclosure: my niece is a beautician.