This is going to get bigger and bigger as the baby boomers age. Look at Florida where seniors are more dangerous drivers as a group than teenagers. The big difference, of course, is that you can punish a teenager. They really aren’t equipped to handle 91-year old murderers.
We can debate the fairness of it, but the fact is virtually no judge in the world is going to send a 91 year old to prison, even for something anybody else would do hard time for. My experience with the courts is that if you are over 80, the worst that will happen is home confinement.