This is true - the casualisation of the workforce is a real problem. If Labor ever gets into power I hope they recognise this as a problem and make it harder to use this loophole.

The best way of handling this, I feel, is to only allow a percentage of any business to be casualised, unless special dispensation is granted. Also, there it should be financially more expensive to follow this tactic - this way those of fixed contracts get compensated for the risk of their employment ending, and employers have an incentive to employee more full time employees.