As an employer, I look at it as a wage that a small business would be able to afford to bring in a possible new member of staff.
I believe the level of wage is considered correct for a young person living at home with no external bills, except personal expenses, ie no rent/mortgage, rates, utilities, etc.
My company's plan for apprentices wages is to pay the minimum wage, and once the 6 months is up, the government grant payment will be used to give a pay increase for the next 6 months. Once the final grant payment at 12 months is paid this will be used to increase again for the next 6 months. So as a company we will be only be paying minimum wage for the first 18 months. Does that make sense?