In all honesty, I don't know. I do know that ERs aren't allowed to turn anyone away due to their lack of money or insurance. Immunizations are often free of charge for low-income people (in PA at least). We're not talking about immunizations though, we're talking abour medical care for an obvious ailment.
I can't quote exact cases, but I certainly have heard of parents not getting medical care for their children for reasons other than religious ones. I can offer anecdotal evidence, plenty of it, but you'd have to take my word for it as it wasn't national headline material.
Any reason other than a religious one. Say the parents just didn't give a damn. Their child was obviously sick, but they didn't seek medical care. Are they entitled to do that? Or, throw in drug abuse if you want to or some other addiction or anything other than religious convictions.
I'm a huge supporter of freedom of religion, I just don't believe children choose their faith. They shouldn't have to die because their parents' faith tells them to pray only. By all means, pray all you want to, that's everyone's right. But, get some treatment as well. To some, prayer is a wonderful thing, that's fine and it's their right.