How on Earth can a cell phone provide sub-meter resolution in position with GPS when GPS only provides typical values of 2.5m accuracy? WAAS can push that to 0.9m, but WAAS is not available outside of North America AFAIK.

It takes more than a good antenna to get good GPS position accuracy.
Maybe no WAAS in Europe but we have EGNOS (European Geostationary Navigation Overlay Service) that can also improve the position accuracy
How on Earth can a cell phone provide sub-meter resolution in position with GPS when GPS only provides typical values of 2.5m accuracy? WAAS can push that to 0.9m, but WAAS is not available outside of North America AFAIK.

It takes more than a good antenna to get good GPS position accuracy.