I may have led you on what could be a goose chase. There may be nothing specific re minors in the UCCC. I feel will find anyone under the age of 18 years can not form a binding contract of any type UNLESS specifically legislated otherwise.
To the best of my knowledge, anyone under 18 cannot enter into a binding contract for anything - and that includes the simple contract of buying retail goods across the counter.
Most contracts of this nature 'stand up', but as a retailer I have had experience of parents bringing goods back the next day, saying they didn't approve and didn't want their child to have the item, and demanded cash refunds. This was for books, clothing, jewelry etc and as the parent had revoked the contract I had to accept the goods back and refund the money.
However, it would have been impossible to avoid selling to minors, but for some items or services, I asked for confirmation in writing from the parent before I would take the sale.
There has been a bit of discussion recently regarding the tattoo and piercing industry, and the legality of selling these services to minors, in that can the minor make an informed decision? Providers of any kind of services have to act on faith that the customer is who and what they say they are, and can fulfil their committments under the contract.
Mobile phone contracts are another area where the provision to minors is troublesome, as they cannot be held to the debt. One cannot sue or be sued until 18, so really in this instance it is vendor emptor!
Generally, their is a separate Act in each state dealing with Minors. Check at www.austlii.edu.au for each state.
It is correct that you cannot contract with Minors as they have the legal status of "infants" at law.
It is particularly important not to rent a house to a minor. Always make sure your prospective tenants have legal capacity.