What happens when a cab driver is arrested?

I'm not sure what direction your question is going so you may need to add more detail to the discussion page.

I'd assume if a cab driver is arrested and he owns his own cab, the vehicle would be towed. If owned by a company, the police might contact the company rather than towing the vehicle.

Depending on the charge or conviction, a driver might lose his hack license as well as receiving points against any state driver's license if the arrest concerned a driving infraction.

If the incident involved drugs or alcohol use while driving, the company could fire the employee.

You should be able to go to the official government website for the State in which you work and read the rules concerning a hack license.