I'm not interested in trying to convince you of anything.
Your first paragraph clearly reflects you've made up your mind, and I am perfectly fine that. I don't give a single
frankly.
I'm not interested in arguing with you.
I have my opinion.
You have yours.
My opinion of your opinion is that it's authoritarian, simplistic, and irrational.
I'm very good with leaving it at that.
If someone who cared about your grandparents driving truly believed they were incompetent to do so, they could have sought a guardianship, provided their evidence of incompetence to drive to the court, and obtained a limited guardianship. We don't need a nanny-state to do that for family members that don't have the balls to take care of their own.