I never understood why we (in the US) treat eyes differently for insurance purposes. I can’t think of any medical device for which it makes more sense to have a single payer system. The positive social externalities from having a populace who is able to see is enormous and would more than pay for itself. Things like car accidents, workplace related injuries, better school outcomes, etc.

But for some reason we’ve gone the complete opposite direction. Not only is eyesight not single payer it’s somehow been excluded from most health insurance and the vision plans that do exist aren’t particularly helpful.