[kd5bjo]

The same way stores keep unattended restrooms clean: periodic inspections throughout the day and a timely response to customer complaints: If cars report to a central facility for a 5-minute inspection after 45 minutes of service, they've already cut labor costs by 90%, but with some increased capital costs due to decreased fleet availability.

[andegre]

I was thinking it would be kind of up to the next passenger. If they are ready to get in the car/Uber, and notice it's extremely dirty, or god-forbid someone puked in their recently, maybe they have something on the app or in the car that says "Report car for service inspection/cleaning" and "request another ride".

[drozycki]

Uber already charges a cleaning fee of $40-150 at the driver's discretion. There's margin there for the cleaning cost, opportunity cost of the vehicle time, and a credit to the reporter for the trouble of seeing vomit and waiting for the next car.