Update.
My domain registrar was offering 1 year .com.au domain registrations and renewals in July 2018.
They are no longer offering that option. I contacted them to ask why and they made up some BS story about how they are working on implementing that feature even though they offered it before. It just shows the lengths registrars will go to, lying to customers for their bottom line.
This is what they said in an email:
" We want you to know that we are not only doing business for business’ sake. Because we value our customers and resellers, we want you to have the best prices the market could offer. And because these prices can increase over time, one way for us to guarantee that you will have the most reasonable deals possible is to have your domain names registered in longer terms. I do understand that you would want to have the option of having it registered on shorter terms as well. This is why our teams are currently working on accommodating shorter registration terms that would suit your needs. It might not be available at this time, but once it will be up in the market, I will personally send you an email to update you regarding these changes. - Dreamscape Networks Corporate Support Specialist "