The issue with consents is quite simple: there is zero risk-assessment in the process, the way Councils run them. Schedule 1 IS risk-based: it exempts small structures, unattached, garden sheds and low decks.
But Councils are terrified of a risk-based system where low-risk=low fees, minimal inspection, and hence lower Power to Obstruct.
And one can imagine their intake of breath once they realise that the world is gonna haveta go multi-proof consent (Councils don't get a look in except for foundations), for factory-built houses, to end-run the slung-up-by-drug-addled-hammer-hands-at-massive-expense approach currently en vogue.
Christchurch has demonstrated to the world that single-storey residential construction, whatever the method (and of course excluding URM chimneys and exogenous impacts like rockfalls) is perfectly safe in a risk sense: it has not killed one single person.
Despite the many and varied 'qualifications' of the builders.
Despite the fact that many such houses (Norman Kirk's was the most famous) were buil;t by the owners.
Despite the fact that many of those houses did indeed become uninhabitable: they took the hits BUT their inhabitants did not. That's the definition of 'failing gracefully' which is the point of most design.
And despite about 60-70% of the housing stock being either unconsented at all (too old), consented during the post-war to 1980's period (when TLA's were responsive beasts staffed by common-sense folk).
The remainder, of course were consented (lately, expensively and interminably) by overstaffed empires full of cardy-wearing nit-pickers whose ideas of customer service came straight out of the Obstructiveness for Dummies playbook.
Additional note: Schedule 1 Building Act 2004 has the following (and, I'm told, rarely used) clause (my italics):