Suppose a working parent or parents have a child who is frequently truant. Working parents cannot control kids while at work. Now suppose they learn they risk jail if the kid continues to skip going to school.
I can imagine some such parents turning the kid over to the county as an incorrigible in order to avoid suffering criminal penalties themselves. Now the county has another rebellious foster kid to place, when they have trouble placing the ones they have now.
The situation is not improved.