My mom and her siblings didn't take away my grampa's car until he was 98 or some shit (he turns 101 in January). He shouldn't have been driving for 10+ years prior to that. Thankfully he never killed anyone or was even in any serious accidents, but his white Lincoln Continental's bumpers and fenders were covered in green, yellow, and other colors from hitting dumpsters, bollards, and probably other people's cars. About 6-7 years ago he was at a strip mall, drove in to the side of one of the buildings, and left without reporting it or calling anyone. Apparently a security guard got his plate, and the cops showed up to his condo to question him. He claimed in his broken polish-english that the brakes on his car didn't work or some shit, so they impounded his vehicle with the intent of checking it out mechanically (he honestly thought they were taking it away to fix it for him). But then the property owner decided it wasn't going to pursue him for damages, and the cops handed the keys back to my mom cause they didn't want to deal with it either. After that he only drove to/from the grocery store, probably at a walking pace. Tough situation, because he and my grandma were still living independently in a condo, my mom and her sister couldn't cart him around everywhere, and he's too fucking cheap to pay for cabs. My dad, bro and I were giving her shit for a decade that he shouldn't be driving, and being assholes, would send her links to news stories of old fogies driving through farmer's markets and killing a dozen people to try to push her along.
So yeah, I agree, there should be mandatory testing every couple years past 60, and past 75 it should be annual. All my grampa had to do was get a note from his doctor saying he was physically fit to drive. Which is fucking pointless, because his doctor was probably as old and frail as he is. Of course he's just going to sign off on that shit. Meanwhile, he's deaf, half-blind, has no strength/dexterity and has the reflexes of a stoned sloth.