More people are killed on the road in accidents caused by elderly folks than drunk drivers. I know this sounds insane, but drunk driving should be no harm no foul.
I've been around for those conversations with grandparents on a few occasions now, and many people I know have too.
I don't think its an anomaly, but it is anecdotal
Varies from state to state - in some states they are illegal under state law or state constitutions, etc. Looks like they're illegal in MI.