> where as Australia's is order of preference with instant runoff (you literally cannot throw your vote away)
This is a tangent, but IRV is horribly broken: it throws your vote away for you, by ignoring all your preferences other than the top choice until it decides that your top choice no longer matters. If you vote A > B > C, IRC ignores that you prefer B over C until it eliminates A. That can cause C to win. That is not a theoretical concern; it's something that you would expect to happen when third parties become more popular.
It is also a powerful force for forcing cooperation between political parties, which trade preference deals.
This is a powerful force for centrism, an important feature of stable democracies - compare australia’s Relatively centrist governmnents and political parties (despite what the stagnation we see at present) VS the vast and expanding gulf between us parties
This is a tangent, but IRV is horribly broken: it throws your vote away for you, by ignoring all your preferences other than the top choice until it decides that your top choice no longer matters. If you vote A > B > C, IRC ignores that you prefer B over C until it eliminates A. That can cause C to win. That is not a theoretical concern; it's something that you would expect to happen when third parties become more popular.