There's no way around it: US healthcare realistically costs about twice as much as what comparable developed nations pay per capita.
That's a combination of a few things:
1) US wages are far higher than most developed nations (50% higher than Japan for example). People often want to blame eg big pharma for costs, or big insurance; in reality, those are only about 1/4 of the $1 trillion over-cost problem, the rest is over-consumption of services and very high wages in the health system (eg radiologists will make three to five times in the US what they do in France; nurses in the US make ~60% more than nurses in Germany).
2) US healthcare consumers consume far more healthcare services than in other developed nations. Americans are used to heavily abusing their healthcare. One of the biggest ways socialized systems bring down costs is by aggressively rationing care.
3) US health is quite poor at the median, thanks to diet and lifestyle in general. Some other nations like Britain have partially caught up to the US in obesity, but the US still leads. Combine mediocre health with a system in which the consumers over-consume healthcare services, and you get an explosion of cost. That cost spike happens to coincide almost perfectly with the ramp up in obesity in the US during the 1990s (the aging boomers also accelerated it).
4) US healthcare consumers have a big layer of separation between them and their healthcare costs. The majority never actually touch the real cost of their healthcare. They're getting their health coverage either through government programs, or through their employer. That has been a big cause of the healthcare cost inflation. The US has a badly structured government-market healthcare system today, that has few mechanisms to restrain costs well (either on the market side or the government side).