I don’t know why (well I can guess that it’s campaign $$), but the Bush administration has been one of the unfriendliest administrations when it comes to General Aviation. At one point after 9/11 some feds were making it pretty clear that they would gladly cut GA in the name of fighting terrorism (even though it was clear that 9/11 was just an excuse).
That's a lot of it. The airlines can out-contrbute GA by a wide margin and get the best Reps and Sens that money can buy.
Fortunately, there are a few Private Pilots in the Legislative ranks, but not enough.
What the airlines fear is the oncoming manufacture of VLJ and air-taxi operators. If they can control the airspace, they can make those operators, and private pilots in general, fade away through financial and bureaucratic pressure.
More fares in their pockets. Follow the money...