It is easy to look at someone of advanced years and make assumptions. Not everyone over the age of 65 has Alzheimers or dementia.   Most still have all their motor skills.   

There is a great deal of bigotry concerning age, and most of it comes from people who have not reached that stage in their life. All bigotry comes from not understanding something that is different from the viewers lifestyle.   Skin color, sex, religion and age are all targets for descrimination. People make assumptions and then try to find sterotypes that fit the image.   

A person with Alzheimers should not be behind the wheel - but neither should a 25 year old with very poor vision or impaired motor skills. Look at the cause, not the carrier.