No you see it is voluntary and they get relevant experience which they can later use to market themselves better and they are not really working since they are training anyways, except that they somehow end up doing the busiwork of their mentors, but that is a super rare exception and only happens to train their work ethics. Also without these positions companies would struggle to create shareholder value and some might go out of business so there is less jobs overall and clearly they cant want that can they?!