[adamson]

How is that an effective repercussion without them also telling you that they're giving you a lower rating for that reason? Do they expect you to somehow intuit over time based on meticulously checking your score after each ride and doing the math?

[garganzol]

A lower score acted as a signal to other drivers signifying the fact that a specific customer tended to pay by credit card.

I found out by talking with some other drivers who revealed such a scheme. It was discussed on local passenger forums as well.