Almost anything would be cheaper and easier than dealing with CASA.
What history tells us, though, is that if any new player even thinks about starting an operation in Australia, the incumbents close ranks and see them off.
So our Kiwi start up would need more money than any of Rex, Tiger, Virgin, QANTAS etc.
Most small operators are borderline bankrupt anyway, so what does this say about viability?
Then there is the usual hassle of dealing with airports to get terminal space. Then cash in hand to get going. Lots of cash. Millions of cash. Look at Free Spirit. Even with terminal space they can't even fund crew training, let alone proving flights.
The Aussie public has been burned by too many past failures to show any confidence with forward bookings, so a new player would need to have a war chest to fly empty and on time, every published time, for six months before anyone with half a brain would book a seat with them.
BNEA320 how many people have to tell you these basic facts of life?