Given the rise of the internet and the availability of price information, and the competition it brings, it's scary being a retailer and being viable in the next couple of years (leaving aside how most retailers are still more expensive in Australia than overseas), isn't it?
There are some things you cannot feasibly ship from overseas by yourself, e.g. large whitegoods. Also a local retailer can provide local warranty where returns are problematic, case in point being tablets because Auspost will not accept Li batteries for air parcels, and it would cost you a motza to return to seller. Then there are the convenience and time factors. It's fine if you can wait 3 weeks for an item from HK but if you need it next week… There are successful local e-tailers in these sectors.