With vehicles, most of the damage is now well understood. There is an accident, people die. Some issues took longer before we understood that they were a big problem (car emissions causing smog, greenhouse gasses, and other airborn pollutants; drunk driving claiming lots of lives) but now, after a hundred years of almost every american being in or near vehicles daily, we have a pretty good handle on it.
Consider tobacco. For a very long time, smoking tobacco was considered healthy. Even when studies started to show the terrible effects, corporations and deniers tried to deny the studies. I remember my best friend's dad saying "I'm not a lab rat, how they do testing is totally different than how people smoke, so obviously those studies are wrong." Now we know better.
And now we have e-cigs. We have studies which show, not proof yet, but strong cause for concern. We have a market full off cheap products which you say are dangerous, and expensive products which you say are not dangerous, and no labelling or education to teach consumers to avoid the cheap shit. And we have people saying "how they do testing is totally different than how people vape, so obviously those studies are wrong."
The harm from e-cigs isn't "you use a cheap one and you die". It's "some products, or maybe all products, emit toxins which are then inhaled". With cigarettes, we know that inhaling certain toxins has little immediate effect but extremely large effects over many years. Do the e-cigs cause the same issues? We're not sure, but it's not exactly rocket science to say "maybe we should study this and put some regulations in sooner rather than waiting until a few generations have damaged their lungs."
I do like your "Reputable studies that actualy say how they tested the e juice come back with no harmful toxins." Do you remember the reputable studies that tobacco companies did which showed no harmful effects? I don't know if the e-cig companies are lying or not; I don't know if they are fooling themselves or not. But I do know that I don't trust companies to regulate themselves; I've seen how that works out.