That can't be it because it fully complies. I am going to go with the API angle.
I don't know /understand all the ramifications..personally use premium membership +Colarado+Trimble navigator but husband uses C:geo when out and about but am pretty sold on the simplicity/ accuracy involved with C:geo to get myself an Android phone. The other day my Colorado and the Trimble had the cache over 30 feet away and the C;geo was 2 feet. Guess which was accurate!
Don't understand all the tech stuff but he has used it...logging on to our account, excluding found caches etc and had no issues at all. Even had turn by turn car directions to cache, google maps , open street maps etc etc. I think it is brilliant!