After thinking about this for a while I have come to the conclusion that the Ayers Rock Resort rule requiring that "all consumers of alcohol be guests" is a rule designed to limit consumption of alcohol by non-guests.

Sounds obvious but one must ask why a profit oriented corporation would want to prohibit sales to outside tourists (non-guests) visiting the Rock?

There is no other venue to buy a beer at Yulara other than the resort. They have a 100% monopoly.

In my mind - perhaps they do not want to have the local Aboriginals visit the resort for drinks and evening entertainment. Therefore, it would be easier to just ban all non-guests.