Hi @oRRs: No I didn't hear back from them. So I've just made the same enquiry at
https://auspost.com.au/developers/support/contactus (doesn't work via FF, works via Chrome).
I now see
https://auspost.com.au/developers/docs/gettingstarted?id=API-Rate-limits-and-Payment-Tiers
Which says
> To help maintain a fair and consistent service to our developers, we rate-limit the number of endpoint requests that can be made from the same credentials. ... X-RateLimit-Limit-minute: The maximum number of requests that the consumer is permitted to make per minute.
Alas, that's still ambiguous as it is not clear whether "consumer" in this context means a consuming set of credentials (e.g. the rate limit applies to requests through your crentials overall) or individual end users (e.g. the rate limit applies to requests made through each IP and crediential combination).
I suppose I'm in a state of what I might coin as "Paradoxical Suprise". That is, I'd be suprised if they did rate limit accross the API key overall, because that would make any mobile app delivery tracker useless. But I also wouldn' t be suprised to learn of a state bureaucracy (under a hybrid private model) putting in place absurd impediments to information which should be readily accessible.
Beyond that issue it is bad design that they've thrown up unecessary hurdles for developers to get access to their api. Some of which you allude to above. So sympathies with that.
However, might I suggest you attempt to jump through those hurdles (
https://developers.auspost.com.au/apis/shipping-and-tracking/getting-started) until you encounter one that is simply too high (that is, not worth your time to jump over, or is simply a block to progress). There's a chance the process is not as daunting as they've made it appear.
Australia Post is (in one important sense) a public institution. Whatever the facts, they *should* be making access to information about this vital public service, in this case tracking info, readily available to any party (providing a service for money or not) helping the public track their packages!