But see that's the thing: already, you've agrees that it probably wouldn't be worth the effort to rate cabs on anything besides a single dimension (rating/quality/stars/whatever). At that point, why not simply have the city compile reviews and then require each taxi to paint it's number of stars on the side?

And for me, it's not even worth that. I just want a taxi that's insured.

I'm not against rating systems on top of what we have now. If it's worth it for you to wait a minute for a better cab, more power to you. (Hell, I might want to take some time to find a nice car if I were on a date or something.) But please don't take away the easy, efficient system we have now in most cities.