And new build tends to be quite a bit easier/faster than a rewire.
I imagine the question here is simply how much work was involved at the switchboard. An old asbestos board full of fuses and crumbling cable is a pain to deal with, even if you're not actually having to get new cable into the board.
I do think the labour rates are probably about 30% high.
CoCs take a while to write and file and I believe some insurers bill per CoC, so reasonable to charge for IMHO.