Canada has 10% of the population of the USA
10% of the people needing treatment, you mean, so 10% of the costs? But then also 10% of the people able to support the treatment costs thus (all else being equal) 10% of the funding. There are much more significant factors than that (and economies of scale would be against Canada being more efficient). Or you maybe have a different point...
and it's also slightly wealthier and frankly Canadians are not as disgustingly unhealthy as most Americans.
Details that are relevant, if correct, but then demands further more specific questions as to why Americans are poorer and Canadians are healthier. Someone seems not to be doing it right, and I somehow don't think it's those in the land of the maple leaf...
The demographic data of the USA, Mexico and Canada are well documented. I won't spell it out for you.
Regardless, Americans won't stand for a 'fat tax' or any other disincentive that places a burden on their lifestyle choices, especially not at a federal level. Politically impossible.
Taxes in the US are supposedly representative by law. So a good example are road and infrastructure taxes that are levied on vehicle registrations and taxes on fuel. Makes sense. Why should you pay for crazy highway projects if you don't own a motor vehicle?
That US legal precedent would not work for healthcare.
If you choose to have unhealthy habits you should be the sole bearer of the price down the road. Its not the style of US law to demand an intentionally fit and young college student to assume to financial liablity of an obese alcoholic old woman needing a 3rd kidney transplant.
So naturally, either the tax is unjust, or the tax places a premium on whatever the government deems is something that puts people in the hospital in order to make it equitiable.
So the country is run by safetycrats and a nannystate saying you need to pay extra for a bottle of wine because some degenerate got fat and expensely ill when all he did was drink wine.