It's the word of one person against the word of another. If it were two men and you had to choose whom to believe, you would probably find it more likely that the lier is the one that otherwise causes more problems, and e.g. gets kicked out of bars.
That aside, they caught the incident on camera, so it is not one person's word against another's: http://dcist.com/2012/12/uber_customer_accuses_driver_of_rap...
Unless there are witnesses or evidence (e.g. camera, sperm, bruises, ...), then, yes, obviously. What else have you got?
But, my intention was simply to demonstrate gender bias by considering two men in a similar situation, the word of a reputable man against the word of a less reputable man. I guess I've demonstrated it...
FTFY.