This is not just the issue of illegals using the emergency room. As Ellemenenope says, any person who gets treatment in ER who does not pay for such treatment or have it paid by some insurance is running up the tab.
For humanitarian reasons one cannot turn away anyone who need emergency care. Those who are so bitterly opposed to any plans for medically treating illegal immigrants don't seem to realize that not having a plan is really the worst way to go. It's ignoring a situation right in our faces.