Folks,
One of the obstacles we face is that aviation is only one small section of the community that uses GPS systems.
In the US in particular, there are many ground based users of GPS/WAAS positioning accuracy.
With the coming of the new generation of GPS, WAAS like accuracies will be available without WAAS, but only to slow moving targets.
Thus, we are faced with a situation where aviation will be the only beneficiary of WAAS, the notional cost can only be spread over a very narrow field, in any cost/benefit analysis.
Of course, in a "user pays" environment, WAAS is unpopular, because gummint/AirServices haven't been able to devise a way for charging for it.
Tootle pip!!