I’m 65 and would happily take a hit for the team. I just retired from 30 years as a family doctor, and I see how people just start progressively losing their mental edge after 70. Not absolutely every single one, but most folks.

An alternative would be a test every voter takes to be able to vote. DMV-like 30-question multiple choice purely on facts of civics and current events. I don’t see that happening given the history of poll tests in our country.