Because all new cars will soon have (and most already have) a drowsy driver detection system. This is also sometimes marketed as a distracted driving detection system. The latter slides into synonymity with impaired driving, which has already come to be synonymous with drunk driving.
The San Francisco Police Department (SFPD) uses driverless vehicles to obtain evidence for investigations, according to IoT World Today. The SFPD has fostered using the footage as evidence regularly, which threatens privacy rights.