The US uses private health insurance instead of a national health service, which explains more than all of the difference in taxation compared to the median country in Europe. If you added what people in the US are paying for health insurance to what they're paying in state and federal taxes, they're paying more than people in Europe do. But if you adopted a public insurance system in the US then the taxes would have to go to that rather than providing revenue to cover existing spending.

The US also has an incredibly cost-inefficient healthcare system, and despite constant attempts to pin it entirely on the insurance companies, the cost problems are primarily related to regulatory capture by healthcare providers and the AMA, which are independent of the funding model. Medicare pays more than countries in Europe do for people in the same age group, because the government can't e.g. limit the number of medical residency slots at the behest of the AMA and then magic away the doctor shortage when they're the ones paying. Which again points to it being a spending problem rather than a revenue problem -- if they'd address the efficiency issues then they wouldn't need such a large government budget.

US per capita government spending is the highest of any economy in the top 30 by GDP. There are only four countries that spend more per capita at all, the largest of which is Norway, which nor only has a public health system included in their number, it also has less than 6 million people and gets a significant proportion of the money from state-owned oil and gas reserves.

If you tried to close the gap with higher taxes then the taxes would come from people in the US, lowering US GDP unless there was a corresponding increase in productive government spending -- which there wouldn't be if you were using it to cover the deficit, because that money otherwise comes from the purchasers of US debt, who are foreign investors, the Fed (when they create new money to buy US treasuries), and large US institutions that buy treasuries to use them as collateral (and thereby result in an economically productive domestic use). Those are the arguments the "deficits don't matter" people make -- in any given year, lower deficits would e.g. reduce inflation a little, but not a lot else. The real problem is that every year's deficit gets recapitalized, and then the interest compounds and turns into a significant long-term problem.

But the "deficits don't matter" people are right in the sense that lowering the deficit wouldn't do much for the economy in the current year. Which means that taking money from economically productive things in order to close it would be bad. Whereas taking money from economically unproductive inefficiencies would be a lot better. Which brings us back to, why is US spending so high when substantially all other countries do it for less?