Because so many people want to do it.<p>Because (unlike acting) the profession was created after the labor union movement was in decline.<p>Thanks to these folks<p><a href="https://en.wikipedia.org/wiki/SAG-AFTRA" rel="nofollow">https://en.wikipedia.org/wiki/SAG-AFTRA</a><p>acting is a much better job than (say) being a model.