Problem of definitions. Personally I don't want any chit chat, so what makes a ride a five for you lowers it for me. At the end of the day I just give service people top marks unless they did something terribly wrong.
Yes, that's the underlying issue with simplistic rating systems like 5-stars -- different people value different things. Even if we all agreed on some standard like "average == 3 stars", everybody has different desires, so my 5-star ride may only be a 3-star for you, and vice-versa.
