Yeah. When you take out rent a car the basic cover is third part liability with a large excess for any damage to the vehicle. So basically you pay the first amount of the claim of whatever the excess. Ranges from 1,000 to 3,000.
If they want to avoid being responsible for any small incidents and flat tyres excess they need to take out excess waiver insurance, either at the desk at an over inflated price of about $20 a day. Or buy their own policy before hiring at $3 a day.