Just to clarify, some head coaches go to watch and others don't. Each program is different because all programs do things differently. But yes, at many of the camps and some showcases, they send the volunteer assistant coach or the unpaid operations guy, or the student assistant, or the grad assistant because they still are considered coaches and assist in instruction and practices in their program. That is the only way they can get off campus to watch and earn some money I suppose. Unfortunately the NCAA won't allow more than 3 paid coaches.
If you want to get in front of the HC, then you might consider attending a prospect camp. Not all HC recruit on the road. It may be different for D3, JUCO, etc.
I don't see much difference between an RC or the other paid coach. They all do the same thing, which is finding the best player that would be a great fit for their program.
Hope this helps.