That makes better sense, but covering costs of extraordinary care isn't an issue in state-provided health insurance (single payer), nor is it an issue with priv

That makes better sense, but covering costs of extraordinary care isn't an issue in state-provided health insurance (single payer), nor is it an issue with private healthcare insurance. With single payer, taxes cover the cost of care for everyone. With private insurance, the costs for more expensive care is covered by the premiums of healthier individuals, which is sort of like what you suggest but does not financially punish people who get sick. What you propose may not be workable (or humane, for that matter) because it distributes the costs of extraordinary care to people who already have more-than-routine care. Presumably these people already have paid their premiums and now would shoulder most of the cost for maladies such as broken bones. EDIT: add missing word "workable".