The internet, as designed, will treat this like damage to be routed around
Australia is an island continent with a very small number of cables transferring data to Asia, across the Pacific and one across the Indian Ocean.
Given that, go talk to a network engineer and ask them how trivial it would be to block things going via half a dozen gateways owned by something like three companies, two of which have substantial ownership by governments. The people on satellite links will be exceptions but there are not a lot of those. Even state to state links go through tight bottlenecks.
The only reason things are not blocked properly is because nobody has put in enough effort (eg. pirate bay is blocked but some proxies are not), mainly because the people that know how to do it (apart from the DSD who want to block all encrypted traffic) do not want to block everything properly (and in the process piss off everyone using a VPN etc). It would be many times easier to implement than "the great firewall of China".
A similar situation will apply to a rural area near you where everyone is at the mercy of the policies of whoever owns the single way in or out.