The AUKUS deal is just Australia shovelling money at the US and getting four fifths of fuck all in return, but that's purely for political reasons.
The corner stone of this system is nuclear weapons nonproliferation. This is, on one hand, unjust - why Australia cannot have its own nuclear arsenal and not be dependent on USA to give them protection? But on the other hand, though, think what would happen if we didn't have proliferation and every second African country had nukes (e.g. Yemen Houthis, Iran, Syria, Sudan, Algeria, etc.).
How Algeria would resolve, say, Algerian-Spanish their territorial dispute if Algeria had nukes and Spain did not?
This system is certainly not perfect, but it worked, we'll see if it will work in future.
Countering the Soviet Union in Europe had the advantage that the countries were accustomed to an existing alliance and working together. In the western Pacific, South Korea, Japan, the Philipines, Australia, etc. are not at all used to working together. Many are traditional enemies with long-termm animus. And the distances are enormous.
The top US foreign policy goal since 2020, arguably, has been to bind them together with each other and with the US to counter China. The US has been amazingly successful for such a short time, but it's still far from NATO levels of integration.
I don't blame them though because they do have a whole country full of about 15 times as many space-constrained citizens next door (Indonesia)
And yes we didn't spend so much on defense as Trump says, but(!) America never really wanted us to be too powerful. They were really happy to play top dog, obviously the more powerful we are as EU, the more viable a geopolitical opponent we are. The US have never really been too happy with nuclear capabilities in Europe and this is the main thing that deters agressors like Russia. Even the UK's is largely built by the US like the Polaris missiles.