You accidentally rating someone 3 for an average service can actually cost them their job. I'm hoping their algorithm uses some sort of a weighted average to offset the ratings of individuals such as yourself who consistently rate very low.
i.e. If I always rate 3, but sometimes rate 1; then that might be similar to someone always rating 5 but sometimes rating 1-3.
Ah, but then a user might throw an Internet Fit(tm) and cause a public outcry about ratings being manipulated by Uber etc. etc.
There are a lot of ways in which a ride can be unsatisfactory (smelly, creepy, crappy car, poor driving, loud music, etc.) but not that many in which it can be exceptional. Unless they show up in a Tesla Roadster or something.
Quoting from http://www.youtube.com/watch?feature=player_detailpage&v=C4r...:
"Engineers do not give out 5s. If you tell an engineer that the possible rating scale is 1 to 5 and they like you, they give you a 4. Because tomorrow they might love you and then they would give you a 5. They probably won't, but they might, so they give you a 4 so that they have room. We all are totally okay with this. But the world is also full of this other class of people who if they like you give you a 5. They're quite consistent about it. 'I like you. I see nothing wrong with that. I'm giving you a 5.'"
The graph (with, admittedly, artificial data meant to portray an example) at http://www.youtube.com/watch?feature=player_detailpage&v=C4r... shows it most clearly, with the satisfaction numbers from engineering clearly trending down. Apparently, engineers don't like to fill out forms, while admins do, so satisfaction survey results also have a sample bias in favor of the 5s of admin staff.
I believe this is yet another case of managers using data without actually taking the time to understand the domain, or use it to identify problems and develop solutions. The approach seems to be nothing more than a facade of customer service.
B2C seems a bit different though you still see more 5s than deserved. Personally, I have no problem giving 4s for good to very good, but not truly outstanding.