The danger is in who gets to define what constitutes reckless driving
That's another issue from what makes car insurance different from health insurance. I would agree that one problem with this scheme is that someone might be an aggressive but safe driver, whereas someone else might drive passively but still get into a lot of accidents. As for basing insurance rates on what kind of car you drive, they already do that. Some cars get into more accidents than others because of the kind of people who buy them (eg, corvette drivers are more likely go out in a fiery blaze of glory than drivers of chrysler pacificas). I'd be surprised if they don't also use your credit score, assuming that's legal.