What are "we" telling coaches?

[Rock Chalk]

In the past week of varsity games I have been told by 3 different coaches that they have never heard that the defender doesn't have to be "set" to take a charge. I know I am going to hear that I shouldn't believe what they are saying, but in all honesty, I believe them. They think the defender needs to be set to take a charge. I explain legal guarding position and all that, and they look like a deer in headlights.

What are other refs telling coaches? Why is this such a difficult concept to understand?