I think what the Australian example shows, and it's fairly instructive, is that competition has been, at least in the Australian example, deemed to be ineffective in bringing down fees. The Cooper review of the superannuation guarantee system in Australia found pretty extensively that despite the existence of numerous funds competing, sales and promotion costs had driven up overall fees. It just hadn't been effective.
So I'm not sure where, in fact, low fees can be found, or how that can be insured in the Canadian instance outside of regulating caps on fees.