[doingtheiroming]

You pass a law giving a class of inspector the right to enter premises where building works appear to be progressing. You strictly limit what they are permitted to observe and record and require recording of reasonable suspicion. Refusal to grant entry is itself an offence.

Approaches like this would work but are also a huge can of worms.

[xxs]

>You pass a law giving a class of inspector the right to enter premises

In most countries (and I'd expect to include Australia), there cannot be a blanket invasion of privacy - and it'd require a court order. The amount of paper would would be ridiculous, then what if I do that on my own, or I used a cousin to do it for me, for free?

[avar]

The customer would be made to sign a contract allowing random state inspection.

> what if I do that on my own, or I used a cousin to do it for me, for free?

You and your cousin could decide to go and mud wrestle crocodiles, but we'd still ban opening an amusement park where that was offered to members of the public.

[Turskarama]

As the customer of a builder, I would very much approve of someone making sure said builders work wasn't dogshit.

Seriously, who in their right mind is going to deny entry to an auditor making sure that your builder isn't an idiot?

[doingtheiroming]

Like I said, can of worms. There are no easy solutions.