Except that most companies don't. Abusive customers are bad for the whole company and the other customers. They lower morale, raise costs, and are generally not worth the money they bring in.
So if a company wouldn't do it for money, why would someone take that abuse for free?
You would accept one of your 100,000 paying customers who comes into your workplace shouting "die die die" and telling you he'd like to cut off your fingers so you can't work any more? After telling him that wasn't appropriate when he came back days or weeks later calling you a simian and shouting at you, you'd deal with it how? By inviting him into your office? I doubt it. I suspect you'd kick him out or call the cops to haul him off.
