I agree this is the fundamental question and disagreement. I certainly don't think coercion is ethical.
I don't either - I'm am anarchist. But, ever hear the saying, "against all authority except mommy?" Kids need some level of coercion just to keep them alive. They have to be made to even eat sometimes.
In a way, I think coercion is a requirement to be ethical. Ethics is determined based on what current society believes to be the right thing to do. We see that there are a variety of different cultures and ethics around the world, which would indicate that humans wouldn't just automatically follow a universal set of rules.
Thus to be ethical in your society, usually means you must follow the rules determined by a collective group of your nations ancestors or you will be shunned/jailed/harmed/etc. Which is essentially coercion. "Act this way or be punished."
We "coerce" children to do all sorts of things. We make them go to sleep. We make them learn to use the toilet.