It's because you can only get (at YMML at least) a VIC 28 times in a year.
The VIC, is limited to the airport.
They overcome this by obtaining a Melbourne Airport Identity Card....the real one. From recollection of viewing the documentation, there's no security checks on it.
The ASIC isn't needed...they are escorted from the gate, to the job site and back again, with a few goons hanging around the job site.
I must ask the old boy how the contractors are dealing with displaying their ASIC....imagine explaining its lost......oh it fell off and is now part of taxyway X.
LOL