Colorado fined them $8.9M last year for violating background check laws.

https://www.denverpost.com/2017/11/20/uber-colorado-fine/

"The PUC said the drivers should have been disqualified. They had issues ranging from felony convictions to driving under the influence and reckless driving. In some cases, drivers were working with revoked, suspended or canceled licenses, the state said. A similar investigation of smaller competitor Lyft found no violations."