I still see many regulated fields requiring some sort of practicum/ internship to accumulate enough hours to obtain an official designation. Many of these are in the health care sector and are often unpaid. Labour is labour, and you should be paid for your work/services rendered. Most of these unpaid "pre-reqs" to obtaining the required designation are in fields made up predominantly of women. The kicker is schools will usually make you pay to stay enrolled while you go work for free. Seems like a clever scheme made up in the past to get some free labour. Trades/STEM have paid apprenticeships/ internships probably because someone someday said: Hey! That isn't right.