It is - that's what makes things like 'rationality' good heuristics - they bind together a bunch of different things that would be unwieldy to get at separately.

Good heuristics should synthesize relevant information and filter out noise. Counting indicators that should have different weights with the same weight is noise. Causing an accident is worse than failing to avoid one, even though failing to avoid one is bad.

As for the 'binary' part, it could as easily be 'how many accidents have you been in?' (followed, perhaps, by 'how many have been determined to be your fault')

Excellent, now we are using the criticism to improve the question. I would further change to "how many accidents have you caused (or been in) in the last year?". Or some other set time. And ask how many miles the subject drives per year in the same time period, to normalize. Other demographic information might help here.