As I've always said, people should wear masks inside. I'm not sure what led to that decision, but there's no doubt that, on a bus or subway, where people might be only a foot apart, everyone should wear a mask to reduce the virus's spread. A mask protects other people, not the person wearing it. That means that, if we want everyone to be protected, everyone should wear a mask.
I don't agree with the decision, and I can't tell you what motivated it.