That's probably because MOH is not something that is going to get a lot of attention so the chances of getting caught might be slim.
Still, you have the facts. It is illegal to use recorded or off air music for this purpose. You can continue to do what you want but as professionals I don't think any of us should be advising or enabling our customers to do anything illegal when we know that it is, as you should now.
Besides, it's more profitable to set them up with a message on hold system that will make them look a heck of a lot better than a local FM station that cuts in and out. Give them the alternatives and the reason they can't use music illegally. If they still insist on a tuner or CD player show them where to plug it in but don't get involved.
-Hal
