This is a startlingly naive view of health care. The real costs don't come from emergency visits. They come from long-term treatments and therapies (Like PonyBoy's talking about). Which is when and where personal means get tested.
And 'uncompensated care' is an issue. But it's not THE issue. As I've said before, the feds could simply cut checks to providers for all uncompensated care, and save probably 75% of what Obamacare is going to cost.