I don’t think it’s about age or an “appropriate time”.
Rather, it’s about a driver’s health/safety and the safety of others (drivers and pedestrians). Eyesight, hearing loss, medication, reflexes, various conditions such as seizures….all these things are factors.
Because of an eye disease (I’ve had 4 eye surgeries thus far) I had to get a daylight only license at age 45. At age 51 I could not even pass the test for a daylight license. Doctors thought they could repair my corneas and retina to get me another daylight only driver’s license, but thus far that’s not the case. There were also a few after-effects of a stroke at age 55. So I had to stop driving and I sold my car. (It was a very sad day.)

But it was either that or drive illegally and with no insurance. I could not take the chance of seriously injuring/killing myself or someone else AND getting arrested and sued. (and...I was never a good driver, anyway. There, I said it.)
Fortunately I’m not isolated at all. I chose where I live partially based on access to public transportation in addition to it being an attractive, safe area, and ease in getting around walking. I also use a transportation service for some things. Also friends and relatives for social trips. Taxis…now and then. Do I miss driving? Sometimes. But I don't miss some of the hassles and expense of having a car.
My mother had medical problems and had to stop driving at age 56. After a spotless driving record, she began to have mobility/reflex issues (had 2 strokes) and one day she hit a fence and my brother got a call from police...mom was disoriented and didn't know where she was. But my father drove (quite well, actually) until he died at age 88. I have several aunts and uncles in their 80s who drive.
OTOH, there are many people driving with no license, suspended licenses, and licenses taken away because of a string of DUIs.)

And a lot who have no insurance. Be careful out there!