A crime completely unrelated to my business may be very relevant to someone I already employ. I have a small business where people are working in relatively close quarters. I don’t want to put a rapist, stalker or some other kind of predator in there with the young woman I just hired. If there was ever a problem that would be on my conscience.
There are all sorts of others I don’t want to deal with either. This is a place where the people I bring in will be around my family, my employees and my customers. I have a responsibility to look out for each of them.
All that said, I wouldn’t hesitate to hire someone with a criminal background if the crime is irrelevant or I assess the risk is low. I don’t care if someone got busted with weed or that they got a DUI 10 years ago. I don’t care if it’s a one time crime related to a very specific set of circumstances that’s unlikely to ever repeat. Or a bar fight, drag racing or dozens of other dumb lapses in judgment that can result in serious charges. But I do care that I’m able to make an informed decision.