They have public insurance. There are no income requirements for public insurance so it's kind of like "Medicaid For All" with a sliding scale. Copay is based on age (10% if you're over 72, 30% otherwise), and premiums are based on income with the poor paying about $10 a month and most others paying $100. Service prices are fixed by the public insurance. There are yearly maximums after which the government pays YOU the difference. There are doctor shortages in some rural areas, but otherwise service is on par with the US and much cheaper. Exceptions would be for super rare disease treatment, and things that are normal in the US like your own private hospital room are considered luxury amenities there.

Hospitalization and surgery are the largest expenses people still worry about, so there are also private insurance companies like Aflac that serve as sort of gap insurance. They pay you for any hospitalization even outside the country, and pay a fixed amount that covers more than your copays, so lot of people have that too.