It's a $30,000 car and the insurance is probably comprehensive. He could save money by only buying 3rdparty liability (the legally required coverage). If you could afford to replace the car, that's usually the better option.
The problem with just having liability is that it greatly reduces the responsibility of others to repair or replace your car if they hit it. Depending on where you live, you might only get a few hundred dollars from them if they total your car.
You may be willing to pay out of pocket if you crash your $30,000 car into a tree, but you'll probably want someone else to pay for it if they run into it while it's parked.
