What do they do currently for alcohol? 17 million US persons have a substance use disorder with alcohol. The closest other single substance even close is marijuana at 3-4 million, opiods at 600k.
Hire extra people to make up for absenteeism, spend resources on substance abuse programs, suffer productivity and quality related problems, probably the same as what your department sees. The tests are only good to know what kind of person sitting across from the interview table from you today. Unless you have random tests after hire, (which our plant doesn't) they don't do a thing for the people that pick habits after you hire them. At least you have a tool that gives you a chance to sort out the potential problems before they become your problems.