It saves needing to update my details with everyone whenever I move.
But it's not really like DNS: my PO Box address isn't really any more memorable than a physical address, for instance.
There are commercial services that do the same thing in the US, at least.
What’s the yearly cost for you? (I’m also from AU)
The cost of a PO box seems to vary based on the location (and even the location within the Post Office if it's large). I pay ~$110 per year for the PO box.
My mail redirect is $165 a year.
Edit: didn't mention it, but I'm also in AU.
My box (I have the smallest size) is $136, and the redirection is $160.
I dunno -- that sounds expensive, but it's like 80c a day, so it's kinda noise ...
It's approximately as good as a dedicated paid PO Box for my usage.
e.g. it's free for receiving stuff I dont want left outside on my front verandah.
I also use my Parcel Collect addresses for web service signup/registrations where I don't want to give out my actual home address.
When mail arrives waiting for me, they send an SMS and I go to the service counter of the post office and show the SMS code to collect.
It's easy to create multiple new Parcel Collect addresses at many Post Offices, on demand via the web portal.