Quality of training is not the point I was making - there are plenty of good quality ATO's across the EU (indeed, you could argue that as far as integrated and a proportion of modular students who train at the large UK schools are concerned, the majority of their practical experience is in fact gleaned from U.S. instructors where there may be fundamental differences in training style and methodology), but rather that potential employers take an interest in where your training is conducted from the point of view of your training background. A clear, traceable training history through recognised providers shouldn't be understated and although this may be of less importance to atypical employers these days, it is still taken into consideration by many operators in the U.K. who have the benefit of a large selection of qualified candidates to choose from who are unlikely to have trained at more than one ATO from start to finish. Records are easily accessible and recommendations from instructors and training managers only a phone call away.
Reputation is also an important consideration - as a hypothetical exercise I think this is quite interesting but as ersa points out, choosing a school based on price alone could cost more when things don't quite work out as planned and additional training is required before skill-test.