My first point is, there are other reasons for this neglect and discussion in addition to not enough money. One is the envirogreen elitists hate the generally unrestricted use by the public of what they feel should be their own private nature preserves (and a number of our "public servants" who run these areas have this sort of attitude),...
...and...
... the purposeful misuse and damage by drug growers/dealers and illegal immigrants in some areas is a significant and growing problem which needs to be addressed before these areas are ruined - not by Ma, Pa and the kids with their pop-ups and hot dogs over a fire but by criminals using these areas for their own nefarious purposes.
Both points went conveniently unmentioned by the author although they bear directly on the problem.
Although he waxed eloquently on many topics from leaky roofs to rotting bridges, he pretty much sniffily ending with the conclusion "send us much fewer people, more government jobs, and much more money".
And, oh, by the way, it's all the fault of that anti-environmental miser, GW Bush!
I've done quite a bit of travelling in the last 6-7 years, and I've visited a lot of National Parks. Without exception, the federal employees that work in the parks as "Rangers" are surly, unhelpful and resentful of you being there. All I've ever seen them do is drive around and tell folks to move along when they are stopped trying to get a picture.
On the other hand, the private concessions that are in the parks were very friendly. After all, they are trying to make a living.
As to your second point about illegals, I've got pictures of illegals selling walking sticks, beads and of all things, scorpions, in Big Bend National Park. When I notified the rangers, they shrugged it off as no big deal. Acted like they could not be bothered to do anything about it.