Well I suppose, that discussions about adding P for all users and requested guarantees were unacceptable to US and building own system was cheaper and more sensible option. It's really not technically comparable, it's difference of generation. I fully agree current GPS services are more than acceptable to many uses, from hiking to field survey. It is NOT, however, enough for aviation. Not because of some stupid political decisions or useless rules and laws. It's just technically unsuitable, a showstopper.