TSA does not establish or fund elite lines. Airlines do.

TSA tried to eliminate them when TSA took over the screening process in late 2002 and early 2003 but that effort went nowhere since airlines pay the rent on the space outside the checkpoint and can thus control who gets to the front of the lines before they reach the WTMD and x-ray machines.

I don't know about the deal between NW and FL at MKE, but my guess is that they share the costs of the private contractor line monitors you spoke to.