Nah, Disney theming definitely is is much better, and more extensive than Australian parks.
It's stuff like how Superman Escape comes out of white shed, or on Wildwest Falls the back of the lift hill is exposed.
At Disney parks you just don't see any breaks in the theming like that, this means more design, more materials etc to finish the job.
HK land and construction costs are high.
Disney capacity requirements are higher, so more trains, more blocks etc.
As for USS, I think because the park is slightly smaller than HK, and yes more attractions in total, but a lot of them are cheaper, for example something like Jungle cruise would cost more combined than several smaller ones like the car ride, rollerskater, carousel etc