Because self policing of the market works so well.icon_mad.gif. And it only takes 1 of them to cause a major epidemic and to spawn numerous NEJM articles.

http://www.washingtonpost.com/national/health-science/fda-finds-widespread-safety-issues-at-compounding-pharmacies/2013/04/11/5321e17a-a20d-11e2-be47-b44febada3a8_story.html?hpid=z2