It wasn’t designed at all. It’s an accident of history. After WWII the government didn’t remove wage controls right away so businesses started offering health

It wasn’t designed at all. It’s an accident of history. After WWII the government didn’t remove wage controls right away so businesses started offering health insurance as a differentiator. They wrote it off their taxes as a business expense. Over time through lobbying and tax code rewites this expense became enshrined and untouchable, to the extent that the foregone taxes are the single greatest annual tax expenditure outside of the military.