This is becoming an increasing problem, and it's causing a LOT of concern because it's forcing people to determine, on their own, what constitutes and emergency and what doesn't. It's a bullshit move by insurers in far too many cases.
Yes, people abuse the emergency room. But others don't, believing that they are actually in medical distress. The person in the article is a very good example. The pain she experienced could reasonably be perceived to be acute appendicitis or even a descending aortic aneurysm. A ruptured appendix can kill you in hours, a ruptured aortic aneurysm can kill you in minutes.
Back to the subject of ER/ambulance abuse... I'm not sure of what the recent studies have shown, but the people most prone to using the ER like a family doctor and the ambulance like a taxi are the poor who either don't have insurance, or who have marginal insurance and who live in medically underserved areas.