Why can't these companies look past ridiculous policies?

Hello, my name is Joshua. I have over 3 years experience as a billboard installer for an outdoor advertising company in Illinois. After moving my family to colorado, for what I thought would be a career position in outdoor advertising, then being laid off after 2 months, I found other work. However, it is still my dream, to get back into billboard installation, of Junior sized billboards, preferably on wooden structures. However, every time I contact a company in a different state, that is Desperately Seeking help from billboard installers, and I tell them that I am allergic to alcohol, so I can’t drink, but I am marijuana friendly, now and then, not everyday, not 24/7, and definitely not well I’m working. It’s just something I do here and there, to calm the nerves at home, just like someone picking up a beer. So why is it that all of these companies in now marijuana legal states, who are Desperately Seeking help, are okay with their installers being complete alcoholics, but not being 420 friendly?