I find CA pretty civilized! I spent many years living and driving in northern NJ, NYC/NY and Boston/MA. Drivers are less aggressive in CA.
That technology could have saved my sister a broken rib, scrapes all over her legs, and a toe that was operated on last week and has metal pins holding it together ... elderly couple did not see her on her bike and ran into her.
so isnt the answer that the need for retest to drive private vehicles over taking public transport comes into play. Some and I not saying all old people do need to retest. its a privilege not a right to drive a car.
My sister lives in Florida, which has a lot of older retired residents. They do retest, but usually you have to do something stupid/wrong to set off the warning flags ... the man driving was ticketed and will most likely have to attend a class or retest. Don't forget that for the majority of the USA taking public transportation is not an option, as it isn't even available.