I think it's not that VIC laws overriding NSW laws, it's just that when you enter VIC, you are now under VIC State jurisdiction, therefore you have to obey Victorian road laws. So if you can't comply with VIC laws, either you leave/return to NSW, or cop the consequences of breaking the laws.
If VIC law overrides NSW laws, that means that Victorian laws applies in NSW, on top of NSW laws itself. That is called overriding.