It's political suicide to tell people they're not trusted to have a license for life because we all think we're good drivers as we're not criticised other than a beep and a hand jesture. The biggest group effected also the biggest voting block, it wouldn't play well in the press as old people would lose thier independence in a time of encouraging old people to not be reclusive.
Events like these are rare, we do have some of the safest roads in the world and I don't thinks there's a big enough public will to make them safer. What's more outrageous is that it's upto the license holder to tell the dvla if thier eyesight isn't upto scratch