Uh?
Have you got your wires crossed, Jobe?
Is that a California thing? Almost all trail building on public lands in the mountains around my place is all volunteer work. The USFS guys supervise and even provide some of the tools, but most of the work is done by considerate folks who want to join in to make the areas a better place, more accessable to all.
In fact, they will even advertise in the local papers requesting volunteers.