Uber enacted their tipping policy to keep total control over prices and moreover to keep prices low. When they were sued by their own workers because of this a

Uber enacted their tipping policy to keep total control over prices and moreover to keep prices low. When they were sued by their own workers because of this and had their backs against the wall, they had to claim it was because of this racist hand-wavy BS. It was a ret-con and an incredibly cynical and insulting thing to do, but that's now the official reason they didn't allow tips.