They don't need to write it like that in the licence for it to be so in practice. A big help for example would have been to say that nobody can remove any right

They don't need to write it like that in the licence for it to be so in practice. A big help for example would have been to say that nobody can remove any rights that he has himself experience. So if it started open, it has to stay open. Mobile providers can modify it all they want but they can't actually control it then. Sure, you can get root privileges and do it anyway, but they've tried to make it very hard and they'll probably continue. For geeks maybe that's not a problem, for the average person it is.