Maybe the area is poorly defined. Other than stating that there is no camping in the day walk area, I don't think there's a lot of promotion of the fact, ie. further defined on maps and in publications/ many signs. Without further definition it quite simply looks like this:

- Screen Shot 2018-09-23 at 12.12.40 pm.png (550.82 KiB) Viewed 47305 times
The camping opportunities are at Lk Rodway and Waterfall Valley.
Despite the (possibly) ill-defined area, most people seem to know the restriction. Personally I think anywhere south of Pencil Pine on that map is justified/responsible. Around the commercial lodgings is as likely considered to protect their income.
Can't see a lot of commercial advantage in closed roads for tour operators. Wouldn't say never though, anything is possible. I'd expect some of the inner circle / big money enterprises will already have exemptions.