It is in the driver's best interests to notify the police EVEN on private property .They may not be eager to show up but there is a lot of liability at stake . Here's a a local attorney site . Do I Need to Call the Police if the Car Accident Was Minor? | Anidjar & LevineSeveral issues here:
1-Accidents in a private parking lot like Costco are not committed on public streets or roadways, so police do not get involved or investigate.
There are a few things which they didn't mention . One is that a driver may have a suspended license or even be driving without one . The cops are the ones who can sort it out.