Assuming the goal of said systems are the same between countries: but they're not.
In the US, the goal of the healthcare system is to produce profit. So the simpler explanation is that the healthcare system consumes more money and produces less healthcare because it spends more to produce profit.
Government chose the system, not the voters. And the government chose the system that benefits the private sector not the population because of corruption(call it lobbying if that makes it easier for you) from the private sector.
I've never heard Americans say "I want a system that costs me a lot, makes other people rich and give me northing in return".
Assuming the goal of said systems are the same between countries: but they're not.
In the US, the goal of the healthcare system is to produce profit. So the simpler explanation is that the healthcare system consumes more money and produces less healthcare because it spends more to produce profit.