There are always going to be people who seek power over others, whether it's under the label of 'government', 'organized religion', 'cult of personality', or any other label. It's just in the nature of some people, just as it's in the nature of some people to blindly follow those they perceive as leadership figures. I don't like it, but I don't expect umpteen thousands of years of behavioral evolution to simply vanish overnight.
All that said, would a society be "civilized" if the government was 100% voluntary?
I don't think there will ever be complete freedom or complete enslavement, we've been pretty much trapped somewhere in between and I don't think we'll ever shift to one extreme or another. We're too varied as a species to ever let that happen, IMO.
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