That ignores the fact that many citizens are prepared and have non-taxpayer funded sources of help. In particular, when one travels on business, the company is responsible for health issues or accidents that occur. As a result, all of the companies I've ever worked for pay for travel insurance which specifically includes coverage for medical evacuations.
Why should the taxpayer be stuck with the bill when my company has already paid for it?
Why should the taxpayer reward people who weren't responsible enough to buy travel insurance?
Why should the taxpayer pay for issues that affect many people, but not for more serious ones that affect a few? For example, somebody gets a heart attack in rural China? The government is going to say "too bad", which is exactly what travel insurance is for.