If No, please provide reasons and suggestions.
There should be no exemptions for owner builders to perform building works on domestic buildings. Likewise there are other exemptions in WA for which registration is not required eg. construction of a farm building ..., and production of a prefabricated or transportable building in a manufacturing yard. I believe that having these buildings being built "unregulated", that is not built by a registered Building Contractor, does not provide confidence in their construction; particularly the structural, electrical and hydraulic aspects of these buildings.
Most importantly there is no need to have subcategories for builders. Let the market place sought it all out. Is it the absence of builder sub-categories that causes non-compliance with the ncc? Will builder sub-categries improve compliance with the ncc? To both questions, NO. There is just vested interest at play here . The "larger" builder does not want the "smaller" builder nipping at their heels in the tender process and lowering the cost of the project. The market place is unlikely to allow a builder with little or no experience in high rise commercial undertaking a project of this level. How do you think the larger builder ever got to this level - by starting as a smaller builder and working their way up. How is a lower level builder ever going to move to higher level? A mountain of paperwork will be required to justify a higher level; and then it will be take forever and a day to get approved. Again it is about vested interest . A monopoly of builders at the higher levels (very difficult for anyone else to ever "break in" to the higher levels). And again the community will suffer with higher prices and it will not ensure that there is greater compliance with the national construction code.
Also these levels are not clear. For example level 3 - single residential (class 1 and 10); is class 1b included or not.
But again there is no need for sub-categories of builders. The existing, and proposed regulations and mechanisms are enough to ensure compliance with the ncc.