My experience is that some people DO get it over time. That is, they know I have a system and that I will follow up with them so they keep their commitment. And because I was a non-GTDer myself for a long time I accept that not everyone will get it when I want them to. Some people will get it when they're ready. Some never will and that's okay too.
There are two things I do now consistently which slowly educates those around me - I use the language of Next Action and I warn people that I follow up on commitments.