To further the devil's advocacy of this topic, what about the draft. That is an even better example of this so called "slavery"

Many counties (although most are moving away from it) still have compulsory military service requirements for young men.

Seems to me like this could be a gross human rights violation.

As another note, one of the basic principles of government is to maintain the order and safety of its citizens. As a general principle, (basic theory, I am not trying to get into this inevitable arguement) educated citizens result in a more "civilized" country. Therefore, governments can justify a forced education. Just like they can justify prisons and mental insitutions (also human rights violations).