It must be nice to stay 25 forever.

Bicyclists do tend to stay in much better shape than drivers, it’s true, but I’m reminded that I know more adults who can’t drive safely than bike and several of them were in good health prior to being in some kind of car crash. The status quo in the US is 40k deaths due to driving and hundreds of thousands of life-altering injuries every year so there’s considerable room for improvement here.

That is not universally true. Health conditions aside age has a big impact here on everything from distance to duration, frequency and speed.