IYet they ARE trusted with a drivers license.
So, yeah.. having seen people drive and the stupidity which that causes I don't trust them and nor do I trust them with a weapon.
Per capita many more people are killed by cars than by guns, but somehow you don't see people calling for bans on automobiles.
But you do see lots of people demanding heavier restrictions on driving, particularly for people who have demonstrated that they shouldn't be trusted with a 2+ ton machine that can travel at 100 miles per hour. Plus, there are more restrictions on driving (liability insurance, mandatory training and provisional licensure, maintenance of licensure, possible temporary or permanent revocation of a license, registration of vehicles, regular checks and enforcement, and so on) than there are on gun ownership. And there are legal liability issues that apply to cars but not guns-- you can be charged with vehicular manslaughter, for example, but manslaughter with a gun is just manslaughter.
I personally would want more restrictions preemptively (before you can get a driver's license), but the last century of US city planning make cars a virtual necessity for a lot of people. Without massive upfront investments auto restrictions would produce serious obstacles for people to live and work. Guns are just not as integral in the practicalities of everyday life as cars are, and so there are different constraints around restrictions of each, fair or not.