You have got to be kidding. An apprenticeship is a paid education system. Many apprentices cost their employer money, especially at the early stages. Is that education not worth the $100 per week you imply they are being short paid.
Most of my peers went into the construction industry and were earning more than I was for my first few years. Some still earn more than I do. I however knew very little when I came straight out of uni. I appreciated and valued the 'on the job' education. Your attitude is short sighted.
The shop assistant and office junior will not progress at anywhere near the rate of an apprentice in terms of income. I know which one will earn more within a relatively short time.