As far as I know all 50 states have always licensed deaf drivers. There isn't even a code requirement on license in my state like there is for corrective lenses. I'm 59 and a kid I went to school with a deaf kid that drove to high school. It's safe enough as long as you do what you should visually be doing anyway by checking front and mirrors as a hearing driver also should be doing.
Today's modern vehicles some of which are almost sound proof with windows up make hearing a siren difficult especially if a radio is on even at a moderate volume level. I find some post Ironic "keep your hands on the steering wheel". Well darn if you're deaf you use your hands to communicate. Now consider this how could he tell an officer he was deaf? Point his index fingers at his ears? Oh that's a firearm symbol now recognized by Morons in public education who call cops and say gun symbol.
For what it's worth I'm hearing impaired but not deaf. I'm at about 50%. With my hearing aids in I can usually hear sirens loud and clear. But let's move the venue a minute to the home. Now I don't put a sign on my door saying hearing impaired resident. I thought about it then thought better. I have to sleep with my hearing aids out although my dog will wake me up.
I am really surprised. I wonder about the quietness of the sirens anymore. They’re just not as loud as they were. And my ‘zuki is very well sound insulated. I seldom wear my hearing aids. The non hearing impaired people live in a really noisy world.
I remember when I got my first ones, and walking out of Wade Park, all the strange sounds. Almost too much to handle. And while driving home I discovered turn signals make a sound, as do the tires on a wet pavement.