Apparently, one issue is not being able to price promotions on baby formula which has reduced competition and kept prices high.
I don't know if it is being done but in medication specific formulations have codes so you can compare products (it highlights Nurofen's rebranding and varying the price on identical painkillers) and that could work here. The news reports say parents go for the big name brands because they want guaranteed quality and something like that code system would help reassure parents that a cheaper brand is just as good.