The problem is that the rating is a bargaining chip and there is no way around that issue.
The rating is currency and is being treated as such.
In all honesty, there should be a "Flag bad ride" and nothing else. No positive ratings. If it was a good ride, you just do nothing. Your rating should be a rolling average of the number of flags you've gotten compared to the population with the more recent flags being weighted more.
That way if you're not flagged as often as most people, it won't matter. Your rating will take a temporary dip. If you're flagged more often than average, it means something.
And flagging a bad ride should be a fairly involved process to prevent people from just using it on a whim. In order to flag a ride, you should have to expend some effort for it.
