That reduces the money available for public services and is unfair on Uber's competitors." Even as Uber has become a transportation powerhouse around the world, opponents, including established taxi operators, have mounted legal and public relations attacks on the Silicon Valley company, saying it owes its success to bending the rules. Several high level executives have left Uber in recent months, and its CEO was forced to apologise after being filmed haranguing one of its drivers. It has hired former U.S. Attorney General Eric Holder to investigate its corporate culture, including accusations of sexual harassment.