And while in the ER, the uninsured can be killed by a "medical error" just as easily as someone with insurance. Quite likely more easily since they are going to get absolutely minimal treatment to stabilize and release.
There are those who have high-deductible insurance policies who never see a doctor unless in unbearable distress because they have to pay for it.
There are those with no insurance that go to ER's for a cold.
You haven't identified the correct populations with which to compare countable deaths.
Under your argument, although medical science saved my life fifteen years ago, I would be better off dead because I may be killed by medical error in the future.
The problem with problem solving is that you must first admit what the problem is.