I wonder what third world countries would be like in twenty years, if the major governments cooperated in the way you described? Would the people in such places be willing and able to dump their corrupt politicians, and move on to something life-changing? No government is perfect, because it's run by people who have their own agendas. But that doesn't mean we shouldn't try to do better, and hold people accountable.
I sometimes wonder what the world might be like if for instance, all the resources that went into military for five years was poured into creating clean energy instead. What would be developed?
Really though, I don't think the vast majority are ready to take responsibility for themselves. But, we keep supporting governments that don't help us- why? Are we fools? Or are we brainwashed?
The systems have been in place for so long, most people can't even accept that there could be anything else. That being said, if even one place changed successfully, who knows?
Pour the world's military budget AND resources for 5 years into anything that could benefit everyone, such as clean energy, and the world has been changed faster than it ever has been. Try that and people will never agree to go back to petty fights amongst world leaders which can and are indeed intended to end with death on a huge scale.