It really depends on the Airport and the business available. In the past they have operated out of places like Alice Springs where Tiger only ran 4 flights a week. That's a maximum of 12hrs a week for the ground crew. Compared to the Tiger Melbourne base which has flights leaving every half hour or so.
Above is spot on, the carriers have the final say. I remember back to when Tiger Airways started and they refused to buy those Mobile Lift Machines for the handicapped, something about passengers crawling down stairs would be cheaper than buying these thousand dollar machines that go up and down. Needless to say the lawyers were lining up quick smart and Aerocare was told to buy the lifts before they were sued.