Don,
I'm with you.
People tend to go where they want to go, or the path of least resistance, the shortest distance between two points,
etc., etc..
There are several ways to make people use cart paths.
One is to place untraversable curbs alongside the cart path, insuring that traffic will remain on the path. Another method is a cart path policy that says, if you're not on the cart path, you're not playing golf here.
From a practical point of view, the cart paths have to be functional to the play of the course, with common sense prevailing. Hiding the paths can be relatively easy provided one takes the time to analyze the play of each hole and the hole that follows, and that the golf course has sufficient room to accomodate the cart paths. Attention to detail is important.
Ran, Jeff Lewis, Jim Lewis and Geoffrey Childs can tell you about a golf course with 17,000+ linear feet of cart paths, with 12,000 + - linear feet of curbing where both are almost invisible to the golfer as they play the golf course.