I'm a sinkie born & bred. I live in the US, have lived here for the past 4 years. Actually, the prices of stuff varies GREATLY from state to state, region to region, even store to store (eg prices at different Walmarts can vary for the same item)
On the whole, yes, I believe Aussie prices are much higher than in the US. In fact, I have a little side business selling items I buy here to Aussies.
Remember, Aussie min wage is much higher than the US's min wage of US$7.25/hr. Hence, you have to pay for that in terms of labour costs.
Oz GST 10%, in the US, it again varies greatly. It's 0% in Oregon and I believe DE & ND. However, states that don't charge sales tax will get their revenue elsewhere eg higher property tax/state income tax/capital gains tax (even if you haven't sold your holdings etc). Some states (I think CT charges sales tax of as much as 12.5%. I think NY is 9.5% + NYC tax etc etc). Here in CO, state tax is 2.9% but there are additional county taxes etc and depending on where you buy stuff, can go up to as high as 8.5%. The area in CO where I live, it's 5.1%, that's considered quite good. Actually, I have never seen only 2.9% tax in any of the areas I've shopped at.
You cannot make a sweeping statement on sales taxes etc
In terms of healthcare, the US system is a shame. If you fall sick or have an existing condition, and are denied or cannot afford health insurance, you're dead. Sadly, the privileged Americans are looking out for themselves and we've yet to see any overhaul. Personally, I'd rather pay more in tax and not have to worry about health and higher education.
Food here, I agree is cheap. Prices fluctuate with seasons/sales so you have to keep track of them, stock up when it's cheap. Now, I'm paying $0.66/lb for chicken legs, milk $1.88 (up from $1.58 before but down from earlier price of $2.99)/gal. Bread $0.78 etc. In summer, fruits and vegs are cheap, in winter, they go up in price because they come in from Cali or Chile. Always buy in season. Mushrooms here are $4.99/lb and up but I hear in oz it's $1/bag. You cannot make sweeping statements about prices. Same with gas here.
Houses, of course, there are now some dirt cheap ones but mostly are in disrepair and/or in bad areas etc. Where I live, the price has remained pretty stable in the housing collapse because this area was mostly out of the speculative market. In high-end (eg Aspen) areas, prices have come down but nowhere near 'cheap'.
Domestic airfares within US/Canada are EXPENSIVE - it may cost as much to fly to the next state over as it is to fly to say Japan from NY/LA (lots of deals by SIA btw)
Just want to make things clearer for the reader. I cannot speak about the Aussie situation, only what I experience here in the US.