i know in the United States at least that one needs a HighSchool diploma before they are eligible to enlist in the army/U.S.M.C/Navy etc. In my opinion anyone should be allowed to enlist, it is a right to serve one's country and is unfair that even if someone attained a GED which equates to a diploma in many scenarios they still can't join armed forces. I do understand that higher ranked officers should be better educated but why do you think that governments are so strict on who can serve their country?
I'm not really sure that this qualifies as a question (more so a statement), but I'll try to give you a constructive answer. First, as others have said, serving is by no means a right. You can actually find that in article 1 of the constitution,which establishes the formation of the United States military. I point this out because your attitude, though understandable, is definately your first barrier.
Next, on GEDs: it's a numbers game. You're more likely to be a problem soldier if you have a GED, as opposed to a diploma. This isn't putting you down; it's a simple fact. Here's the kicker, though...if you start taking college courses, the GED vs diploma issue becomes moot, as the military (Army, at least) looks at your highest level of education. Will a couple completed semesters get you in? I'm not sure; 10 credit hours was the standard a couple years ago. I can tell you that an associates degree got my newest soldier out of MEPS and into Basic, and he had one of those 'diploma mill' GEDs...the ones that got black-listed a few years ago.
Your next mission is to start calling a recruiter regularly, and keep him/her posted. Enlistment requirements change just about every fiscal quarter. Sure, getting in is tough, but fortunately for you, staying in just got a lot tougher, so persistence pays dividends.
My source for this information is a briefing I received two weeks ago, as part of a Leader's Course. For those of you who've been there, it was just like it always is...Army can tell you everything you don't need to know ("your 17-year-old cousin can choose from these jobs"), but is still hazy on the pertinent stuff ("it hasn't been decided if a soldier who _____ or _____ will be able to stay in"). I guess it's good to know what the new crop'll look like, but so much is up in the air right now for those currently serving that it's definately nerve-wracking. I digress...
Maybe it's not the answer you want, but i hope it helps.