Although anecdotal, multiple family members who are health care providers in the ER (Nurse, PA, Doctor) it's more often than not far from an emergency ailment. This creates a scary supply and demand scenario.
1 - Any time a condition/illness causes bad nausea/vomiting, the urgent care will send you to an ER to get IV meds and fluids, which they can't do. You probably don't need a full ER, but that's the only place to go. This must be fairly common during flu season, and a huge waste of resources. A startup idea could be an Uber for off-hour home visits. If all you need is IV fluids, check some vitals, keep you comfortable to ride-out a nasty virus, surely it's in everyone's interest to have a quick visit by a nurse/PA, possibly MD.
2 - Pain management. If you have a relatively new illness or injury that requires stronger medications to manage the pain, you have no choice but to go to an ER, or perhaps be admitted to a hospital (which is even more expensive). I can't say if over a longer period of time, for a chronic case, there are better options that eventually get worked out. But 2 months into such an issue with a family member, and going to the ER was frustratingly the only option.
3 - Chest pain. Yes, it could be a heart attack, so maybe an ER is the best place to go. You will get triage pretty quickly with an EKG, and some basic vitals, but you're still stuck there for hours if it's a false alarm (I'm guessing quite often). There's got to be a better way.
For that reason, I visited ER twice that week, and was diagnosed with some mild stomach issue and stress. Every single test they ran gave negative result. It's a huge waste of time for me, and I feel very guilty for wasting ER resources (especially as an immigrant). There has got to be a better way.
Edit: I was very lucky to be covered under school-mandated health insurance, and I don't think you could live comfortably in the U.S. without having one.