Not the whole problem, although your comments are certainly part of the problem
Also, are the imported workers well qualified or just simply hard workers who protect their turf
TAFE was commercialised
School standards were lowered
Training courses were decimated, a 5 year apprenticeship became a 3 month course
Apprentices were paid such high wages that employers could not waste their time in training them
The government in collusion with Unions deliberately wrecked any chance of producing enough Australian tradesmen or women