The average American adult needs a vehicle, but does not need a gun. A gun has only one function- to destroy. Vehicles transport people, objects, create privacy, and are sometimes home. They're used almost every day. Guns? Not nearly as frequently.
Also, there is plenty of reaction about vehicle deaths- it's a known problem that our aging population is going to be less capable of driving themselves as years go on, being unsafe, and the ubiquity of cellphones has increased the threat of distracted drivers. We have laws and examinations about qualifying for a license and strict penalties for operating a motor vehicle while intoxicated (not as severe as, say, Germany, but the point stands). Every vehicle manufacturer touts safety as a selling point in its ads.
Cars are ubiquitous, and some particular political bodies have made it difficult to construct and implement mass transportation as an alternative to cars. Guns, less so.
Nobody is coming to take away your guns even if the gun regulation boogeyman ever grows fangs. Pandora's box is already wide open, and it's too convenient to rally the masses by claiming that the libs are gonna steal your rights, so it's not actually going to happen anyways.
Come on, you know a tragedy by accident is wildly different from a tragedy of malice and is going to be wildly more meaningful to different people. You don't have to care about every tragedy, but don't bemoan those who might.