While I am sure that UBER is probably, in many ways, a fine company, the reason why you would not hear complaints is because a driver who is caught complaining would be swiftly dispatched.
Complaining could result in the less than 4 star rating which could result in termination.
Why complain if you appreciate the opportunity? Conversely, why do the work if you do not like it?
As to being dispatched for complaining, you do not understand the nature of the relationship between driver and dispatcher.For the Uber driver it is “my car, my choice, when, where and how.” The driver is under no obligation to serve a client who makes him uncomfortable.
The big complaint is by taxi owners who pay upwards of $1 million for a license and hire drivers to stay on the street 24/7. It is a cut throat business with high rates and surly service. UBER has broken into that closed shop with better, cheaper, more satisfying service.