Wonderful subject.
A few points at random:
1. GPS is in widespread use in Europe. The incentive to create GPS approaches has always been much less than in the USA because of the WX. Far, far more European runway ends have at least Cat 1 ILS so the business case (which is what it's all about) is poor for the incremental advantages. And there is far, far less GA/bizav looking for GPS non-precision approaches which has been a huge US driver.
2. As has now become apparent, GPS Cat 3 approaches, which are what are needed by the people who actually pay the bills in Europe are a long way off - if do-able at all.
3. I spent hundreds of hours discussing GPS with US FAA and related officials in the mid-90s. They frequently, honestly could not understand why Europe wouldn't just jump for it. I used to say: take a look at all the literature on GPS, substitute the word French (or Austrian, or Greek or even British) everywhere it says US and then consider how the USA would feel about signing up to a system entirely controlled by those people. An effective argument I found.
4. Aviation is a tiny user of GPS/Glonass/GNSS. It only matters at all because a) it's got an exceptionally fierce safety requirement and b) it's got deep pockets. But GPS etc at the moment is very heavily about job and technology creation and protection - there are public domain reports on both the US and European sides making this totally and unashamedly clear. In government circles nobody really pretends otherwise. It's a multi-billion dollar/euro industry for a good few years to come and there is absolutely no way Europe is going to let it pass by.
Stop me, I could go on...