Yeah, people aren't morally good enough for true anarchy to work. Like DAS said, you get Africa when you have true anarchy.
This is wrong for a few reasons.
First of all, we can't really talk about human nature (as shown in your sweeping generalization of what "people" are) because what we see today isn't what people are naturally prone to do. We have been born and molded by unnatural conditions surrounding us, as seen in the existence of a state. To even take a guess as to what human nature would be, you'd have to look at nature and see how plants an animals cooperate without the existence of government.
Second, our governments exist through physical and mental violence and we've been exposed to this violence since the day we were born. Our lack of "moral good" is the result of our existence being an exchange of violence to get what we want. The state has prevented us from cooperation and limited our mentalities to competition.
Third, to put it as politely as I can, Africa might be the worst example as to why anarchism cannot work. Africa is the result of foreign colonists drawing arbitrary lines in the continent without any respect towards the location of different tribes. If we had let each tribe control their own devoted piece of land, the continent would have succumbed to the violent power vacuum it is today.