I've done some research on this topci and my understanding was...

1) Australian based/licensed companies cannot offer online gambling products to non-Australians; and

2) Companies without Australian licences cannot offer online gambling products to Australian residents.

So until Ladbrokes becomes licenced in Australia (or obtains an Australian Licneced company) they can't do it. Even online poker sites should not be accepting Australian residents unless they have the proper licence but they do as it's a very hard to thing to enforce. However I think Ladbrokes are loooking to acquire an Australian company soon so they are probably trying to behave

That is the whole reason why Betfair had trouble when they started and they had to get a licence. Even then the licence is quite restrictive which is why Australians are still not allowed to use Betfair games site (poker, blackjack etc).