Not quite. Vendors can now legally add a surcharge to cover the cost for payments from a credit card. Some vendors traditionally refused Amex when they had to eat the charge, since Amex was something like a 4-5% cost to the vendor as opposed to the 1-2% costs of the other cards.

Why, in a small, stagnant market like ours, do we fare much better than the US system?

We have strong banking regulations, apparently. I heard somewhere that during the GFC, there were only ten banks of that kind globally that hung on to their AAA credit rating, and all four of the Australian big banks were in that ten.