I would never knowingly dive with an op who does not pay their employees. By "boat crews" what do you mean? Typically on a small boat the only op people are the captain and the DM.I have had boat crews mention they were basically unpaid interns in Cozumel and relied on tips. I mostly dive with a family run operation so I believe they are all paid in some form. I understand the diving is cheap in Cozumel with the agreement you tip. Works for me.