Of course it's less expensive than public school, CC credits usually cost somewhere around $70. It was $50 for me... I got two years of my college education for 3k, and it all transferred to my four-year school.
I thought about this, but then decided that this explanation does not make sense. The state pays the public high school the $6,000 or whatever, per student, then the high school pays the tuition for the student who is attending the junior college. The only benefit that I can see to the state would be not having to subsidize the student's tenure at the junior college after graduating from high school. But there is no guarantee that the student attending the junior college for free while the state pays the high school for him or her will continue on to a state 4-year college, or as a resident of the state and pay taxes, etc., etc. So I still don't understand why the state thinks it is less expensive to pay the high school for the student while the high school pays the junior college for the student, and the student attends the junior college for free.