Given the Tax Policy Center estimates that over 45% of households will not pay federal income tax in 2015, the overlap may not be as great as one might initially think.

I would say that the NPS concessionaire policy is perhaps regressive, but then again, as you readily point out, the price of lodging in the park system is not for the faint of heart. One place there is no overlap is the foreign visitors to the parks. So I guess that is a benefit for the U.S.

The issue is the government-institutionalized monopoly and the tight supply relative to the high demand for rooms. As long there is more demand than supply, the pricing will be higher than if competition existed.

We were in Big Bend over Christmas and the only lodging in the park was booked months in advance. Even front country campsites in the Chisos were full.