There are also medical conditions that happen so slowly, people don’t notice them. Here in Germany, no medical examinations are required for older drivers. You are 80, can’t walk properly anymore? The car lobby will fight for your right to still drive your SUV. Or else we would have to think about rural public transportation.
Before I had a cataract surgery, I thought my vision was not good but acceptable, just need new glasses. Only after the surgery I realized how bad it was (there are some weeks between left and right eye surgery, so one has a side by side comparison). Good thing that I stopped driving cars in 1995.