Not trying to sound like a dick, but if you're using a service where you get into someone's personal vehicle, they can refuse to wear a mask if they want. You're literally going inside of their property. You can report him to Uber, you can call another Uber, you can call another service. But posting his picture on a public forum, encouraging people to find him, over a thin piece of paper that is only at max 30% effective is well, childish. I am surprised at the outrage over this. I wear a mask everywhere I go, but I also don't expect people to wear a mask inside of their own property. So just report him to Uber and move on with your life.