Why Don't More Courses Use Marshalls?

In my area (Nashville) there aren't nearly enough public courses, so every course is packed and backed up on weekend days. I don't mind a slow round, since I'm used to it. But I can't stand when I see a group that is a hole or two behind pace.

To clarify, to me, pace has little to do with the time it takes you to play, and everything to do with how close you are to the group in front of you.

I don't understand why more courses don't have a Marshall out driving the middle-6 holes and making sure everyone is keeping up properly. Surely there's some maintenance or shop employee who could add that to their regular list of duties?