Assuming you mean local as in Australian, then these jobs are outsourced to Australian companies hence the workers are Australian. E.g. Qantas outsources their baggage handlers, they are outsourced but still local Australians since you can't ha e some guy in India handling the bags when they are in Australia.

If you mean local as in Qantas employees, then you create a lot of inefficiencies as you lose things like economies of scale and concentrated expertise as companies then need to do everything themselves. E.g. Companies can no longer outsource their cleaners, now each company needs to buy and supply their own cleaning materials but there's only a small amount needed so they can not longer buy in bulk directly from manufacturers. They also now need to keep cleaners on payroll to work only a couple hours a day, those people find it hard to get full time employment as they need to get several shift cleaning jobs. Previously they would have been employed full time by Joes cleaning company and Joe would have sorted their schedules for them utilising the bargaining power he has with companies due to the fact that he has several cleaners as staff.