As you say, one thing the bus industry are struggling with is convincing people it is safe. Having to wear a mask subconsciously reinforces the idea that it is not safe, but I agree that without masks the safety idea will be a problem.I don't think removing the requirement for masks will help though. The basic problem with public transport is the risk of catching the virus - increasing that risk won't bring customers back.
I do wonder whether masks do reduce usage by those who think the industry safe. Masks are unpleasant to wear. Maybe I've read too many comments in the Covid forum!
Very worrying numbers though. I get that commuting is still reduced, as is leisure, but even with that it's really bad to see. And you have to worry that people will find new habits and not come back.