I can't advise on the insurance side Stewart but I can tell you that some hospitals will physically detain you until the bill is paid, this is officially illegal but it does happen.
When I was checking my partner out of hospital when our daughter was born, I was a bit short of cash as she gave birth the day I arrived, they wouldn't let us out till I had paid the bill.
The bill was in two parts the hospital fee's could be paid by credit card but one of the consultants demanded her fees be paid in cash, so I had to run round trying to find an ATM that my card would work in, they have ATM's in the hospitals near teh cash desk for exactly this purpose
but I had a bit of trouble that day, we got out eventually though.
My son and partner have also been hospitalized a couple of times and on both occasions it was clearly awkward trying to get them back out, plus it's not like here where they want the bed empty as soon as possible, over there they will come up with any excuse to extend your stay and increase your fee
I have also heard of people having problems even getting in to a hospital without being able to show they have the means to pay, but they usually assume a westerner will be able to cover their costs.