> That's the classic question of when the state should step in to correct bad parenting, and when it should leave well enough alone
Well, no, this is the slightly different classic question of whether, in order to prevent (or, more realistically, on the pretext of preventing) bad parenting, the state should impose a universal totalotarian papers-please approach to basic life activities which requires everyone to prove identity to refute the assumption that they are a child so that it may impose its own (also bad, because totally one-size-fits-all and corcumstance blind) parenting on every child, without regard to the imposition on the liberty of every adult necessary to do so.
Stepping in to correct bad parenting happens when there is a system to identify bad parenting requiring correction and intervene only where such is identified, not when you are imposing a universal regime on everyone on the justification that without it, some will act as bad parents. While both are approaches frequently proposed, they are different and should be distinguished.