It's important to clarify some misconceptions in your question. The Canadian healthcare system does not typically provide free or cheap treatment to US citizens. The Canadian healthcare system is primarily designed to serve Canadian citizens and permanent residents.
Canada has a publicly funded healthcare system known as Medicare, which provides essential medical services to Canadian citizens and permanent residents at little or no direct cost at the point of care. The funding for this system comes from taxes and is intended to ensure that all Canadian citizens have access to necessary medical services regardless of their income.
For foreign visitors, including US citizens, the rules and coverage vary depending on the province and the nature of the medical service needed. In some cases, individuals may have to pay out of pocket for medical services or have private travel insurance to cover their healthcare needs while in Canada.
On the other hand, the United States does not have a single, universal healthcare system like Canada. In the USA, healthcare is primarily provided through a mix of private and public systems. The US healthcare system does not provide free medical services to US citizens, and individuals typically have to pay for medical care through private health insurance, out-of-pocket payments, or government programs like Medicare and Medicaid.
It's also worth noting that some Canadian provinces may have reciprocal healthcare agreements with certain US states, which means residents of those provinces may receive limited coverage for emergency medical services while in those specific states. However, this is not a widespread arrangement, and US citizens visiting Canada usually need to have their own health insurance or be prepared to pay for medical services if necessary.
In summary, the healthcare systems in Canada and the USA are structured differently, and both provide care to their own citizens and residents, while foreign visitors generally have to cover their healthcare expenses through private insurance or out-of-pocket payments.