I spoke with a driver yesterday about it and he says he will basically pick up anyone above a 4. This was in NY so might mean different things in different places and to different people.

I'm not a driver, but I know enough about Uber to answer this...

Drivers are prompted to rate their passenger immeditely after the trip, in the exact same manner as riders rate their driver. Then, when a trip is offered to a driver, they're shown the potential customers rating (and other details), then the driver will choose to accept the job or not

I ask a lot of questions: The Uber training, apparently, is that driver's should only ever rate their customers a 5, or a 1. That's it. A customer is either great and a 5, or an asshat and a 1.

I don't know who told you that, because that's not what I was told. I drive for Uber, and there aren't specific 'codes' for ratings.

On lyft, on the other hand, 5 means good, 4 means needs work, 3 means "don't match us up again" and 2 and 1 mean "recommend deactivation", 1 means "dangerous".

Then why didn't Uber make it binary?

To avoid a db migration ;)

it's actually really hard to tell what the passenger rating is. It only flashes on the screen momentarily. Lyft, on the other hand shows it up until you pick up the passenger. This is helpful, one time I called a passenger as a courtesy and got a really really belligerent tone, and i noticed his passenger rating was really low, and so I told him, "sorry, not worth the effort".