If the police have the rego. number of the car then they can go to the registered owners address and place whats called a form of demand on the registered owner. This form of demand requires the registered owner to provide the drivers details of the car when it was allegedly committing the offence. The registered owner commits and offence if they fail to supply the details.
It's very handy when it comes to investigating motor vehicle collissions where the registered owner wasn't driving the car at the time of the crash. Also when people don't pay for fuel or when police, like in the mentioned scenario, have something else more important to go to.
BTW Brad, you're talking shit.