The transposition of the American model to Australia did not fit a 'like for like' argument in respect of radar coverage, frequency access, sector size, controllers 'per-capita,' etc, etc. It was just not 'like for like' as regards fundamental ICAO requirements when it comes to importing another system and relying solely on an 'Implementation Safety Case.'
This is fact, Dick.
If you want to 'import' the US system, you have to import the US system in whole.