Most of the time it's probably determined by what results in the least work for the cop.I'm not sure, I think they have ""leaving the scene of an accident" here but I think it's depends on the severity.
In other words, if there's another car involved or someone gets hurt.
I witnessed a bloke in his mid 20's run a red light and t-bone another car on Springvale road 20 years ago. He managed to back his car out after a bit of an effort, and then take off up the road while his victim was injured in the car. I was out of the car trying to assist the injured victim.
Police turn up 10 minutes later. 20 minutes later an old bloke with a white beard turned up in a different car and said he was the driver and just went home to change cars. Said the light was green
I told the police it wasn't him and the light was clearly red, had about 5 other witnesses saying the same. They just shrugged and said he said it was him so that will do. , didn't want to do the paperwork. Breatho'd him and was all ok - no fine no problem.
Police are probably the laziest profession I know.