I would imagine if a shop was caught with a book full of fake names and zero QR code sign-in. That's a $5K fine to the shop and every punter there who didn't "really" sign in also gets a $1K fine.
That's a pretty expensive punting session there.
Surely they won't check every shop, but they will try to make an example of a shop if a council inspector went in or some disgruntled punter complains.