It is alleged that Uber has a secret tool they use internally, named Greyball, to identify and evade government authorities who try to clamp down on the cab hailing service.
Greyball apparently uses data collected by the Uber app to identify and then deceive authorities through different methods including serving up a fake version of the Uber app populated with non-existant ghost Uber cabs on the map to ensure authorities can't call and catch an Uber, orin some cases, not display any Uber cabsat all.
One of the cities Uber used the app in is Portland where it was revealed that authorities would constantly fail to get an Uber and if they somehow managed to hail one, it would be cancelled immediately. A common thread among cities that Uber used Greyball in is that they either banned Uber or had strict regulations around Uber.
According to the New York Times, Uber began operating in Portland (2014) without the city's permission. As a result they were in violation of the city’s Private For-Hire Transportation Regulations and Administrative Rules.
Uber's Greyball is allegedly used mostly outside of the USA to evade officials and currently no reports or evidence of it in any of Uber's Afrikan markets.