The problem here is “what is best for the patient” is a value judgement, not a medical one. The hospital is doing nothing upstanding by deciding that the child is better off dead sooner than later. They are simply using the power of coercion to enforce what they think is the better judgement. The parents or guardians have every right to make that call, but because the hospital staff disagrees that somehow trumps them. On what basis I do not know, as it is a researched and documented fact that medical personnel, no matter how well meaning, routinely value the lives of their terminally ill patients less than the patients themselves or the parents/guardians do.
This is not a “my culture is just different than your culture” issue. Especially considering that all English-speaking, European-decended countries are nearly identical culturally and vary only in fairly meaningless ways. This is an issue that goes to the natural laws governing the mother-father-child relationship across humanity. Saying that the UK just cares more about the patient than others is disingenuous and is a hand-wave at criticism.