45000 Americans are killed every year driving. Funny thing though. No one wants to take away their cars. They're willing to put up with the carnage. And get this. About half of the auto deaths was caused by drinking. Yet, amazingly, we reversed a constitutional amendment that had stopped the manufacturing of alcohol that could have saved thousands annually. Silly us, we're now legalizing marijuana, state by state, that's going to add to the carnage on the road to the tune of hundreds of more deaths a year, a lot more than occur with mass shootings. And there's no constitutional protection for any of these things like we have against eliminating guns. We could stop it and the Supreme Court would not interfere. We're a strange people. 
Let's see if I get this: you claim the USA has no laws (with teeth) against driving whilst under the influence of alcohol or other drugs? Traffic deaths, unless due to such self-inflicted reasons as drugs, booze and suicide, are due to accident, which by definition can hardly be prevented unless you refuse to maintain your vehicle properly, in which case you are culpable. Unlike guns, whose only raison d'ĂȘtre is killing, cars are a means of transportation, nothing more or less. The logic you have attempted to apply with such a concatenation is unsustainable.
Gun deaths, however, may happen because of booze and other such influences, but accident is due to carelessness and that hardly causes the mass killings that bring guns into more visible disrepute. You don't set out armed with a shit-load of magazines (not of the reading kind) and guns, intent on public mass murder, by accident.
The booze industry brings in a lot of money: as ever, cherchez la femme, or in this case, the loot. Just like your guns, then.
Regarding legalisation of drugs - I agree with you: it beggers belief and makes one wonder how many politicians have a vested interest in not getting arrested for having their version of a good time and a runny nose.
Yes, you are a strange people indeed; nobody could sensibly argue with you on that one. Trouble is, you are not alone in your strangenesses. So far, I don't think you've done a Brexit! Well, only in minor ways like nuclear non-deals and Paris Accords on climate... thing is, as with Brexit, such little moments don't just affect yourselves.