Roughly 2,000 times over the past 17 years, Marguerita Toribio, an illegal immigrant from Mexico, has climbed into a cushioned recliner for the three-hour dialysis treatment that keeps her alive. She has never seen a bill. U.S. taxpayers have covered the entire cost of her treatment in California: more than $500,000 and rising, not including a kidney transplant in 1993. The kidney failed when Toribio briefly moved to North Carolina, which refused to pay for her anti-rejection drugs. She needed to go back on dialysis three days a week to clear toxins from her blood, but North Carolina didn't cover...