The difference with IOS is it is a single manufactured phone with exact hardware..easy to update. Android has so many different variables when it comes to updates. The google line of phones receive updates from google. Most other manufacturers rely on carriers to push updates, as the carriers need to add their crap to the FW. HTC is a low priority for Telstra. Just look how much quicker Optus/others receive the update...can be 3 or more months in advance. Telstra could push updates quicker if they needed to, however most people don't really know or care about updating. This is how Telstra works Edit -definitely not barking up wrong tree...Telstra is responsible for updates full stop. They should be released when HTC provides them, not months later.
Previously worked with a Telstra Partner however I am not a Telstra Employee, just a fellow customer helping when I can.