Mandatory volunteerism is not volunteering. After new uniforms, perhaps we should replace our blackboards with telescreens. Calif. Requiring volunteer work is no more slavery than requiring that students do homework or run around a track during gym. A requirement for graduation is not a law. The choice, however, is still there, with no legal penalty.
Slavery is involuntary.
Community service is not. The Iowa 'miracle' is but a celebration of man and science. The multiple births were the same sort of miracle as having 50-DD breast implants.