Car crashes aren't contagious, car crashes don't mutate, and car crashes are more or less constant.... (although I imagine more car crashes do happen around holidays than the rest of the year).... Basically what I'm getting at as far as them being more or less constant is that there is virtually zero risk of car crashes causing a sh*t show type situation where hospitals would be overwhelmed with car crash victims.... unable to tend to all of them. That can't be said for covid. Especially at the beginning of this. We barely even knew wtf it was. Simply "letting it rip" would've been incredibly irresponsible.
But to once again go along with your analogy anyway.... If an area gets risky to drive through with your car (flooding, snow, ice, etc.)
............ They do shut down the road.
:o
There are also multitudes of ways they have changed cars over the years in an effort to make them more safe, less risky, save lives and such..