If I understand this properly, it is a gratuity. The way I understand it, the taxi is still a normal taxi in operation but essentially has hooked into Uber to give it a new way to find fares and to have people pay. If this is the case, then the rate is the same with or without Uber and you still need to pay the gratuity and Uber just automatically selects that gratuity to be 20%. It's actually appreciably different from Uber choosing a rate and then adding a 20% automatic gratuity on top of it.