From a financial point of view it is not worth putting on an apprentice (most leave at end of term or soon after - so rarely an investment in your company).
The first few years they certainly are not worth that amount in most cases, so they are put on as an aircraft worker (not apprentice) for a slightly higher rate but work 13 weeks more.
While an Australian company can have say a LAME employed at $120,000 they can advertise for another at the award rate of around $52,000. It is not likely they will get any takers.
But they can not get in a guy on a 457 and pay him $52,000 - the 457 must get the same as the other LAME being $120,000.
That assumes they have the same licence.