It's not age discrimination. Just like we all had to take driving tests to get our licenses, we should all have to continue taking tests to make sure that we are still mentally and physically capable of being able to drive safe. You don't let your friend get in the car and drive after 10 beers do you? Then why would you let someone who can barely hear and/or see drive? When people get older their response time declines, and should be tested in my opinion at least every year.