This is the reason why the US system is better than Canada. In Canada you can't shop around and need referrals for specialists.
Healthcare is much more than being operated or receiving some treatment for a rare condition, both things that are very much researched and done outside the US both privately and with public money. Healthcare is also about allowing people with health problems to live with dignity and allow then to function in society. To care for the weak and not only to restore productivity of a broken cog. Healthcare is about a strong first line of care that prevent conditions to get worse and irreparable. Many countries with a thousand or less of US's GDP can teach a lesson or two on that. In any case, most countries are slowly copying many aspects of US healthcare, I guess it must be indeed be better, or perhaps more profitable.
US is also able to attract the best professionals, including MDs. Here in Canada we're left with the "leftovers". Those that did not make it big in life.
the US just uses ERs as an infinitely shittier but equally costly version.
You can't even shop around for a family doctor. You have to sell them accepting you as a patient. With that power inbalance you better follow what they suggest and avoid questioning too much or you won't have a doctor.
With HMO's, you're guaranteed someone will be assigned to you. With traditional insurance, there's a big labor shortage, and there are often <= 1 doctors accepting patients in some towns.
In the USA you literally shop around. They advertise. You can literally look for the best surgeon and ask around.