An ER is not like this. Sure, we can stop ambulances from coming. This is called going on diversion (and hospital administrators really hate that because it's medical dollars going to another facility.) However, the ER must at least address every patient that walks through the door.
8. Slow specialty response. If your care hinges on hearing back from the expertise of a consulting physician-- then everyone is waiting. Us. You. Everyone.
9. Overwhelmed support services. Support services like lab, radiology and pharmacy aren't just accountable to the ER but to the whole hospital-- including outpatient services. So, if they're overwhelmed, it will cause delays in the ER. There can be other critical patients than those just in the ED.
Hopefully, this gives some insight into why your ER wait time may be more than you'd like it to be. Although the current culture has equated emergency room care with expedient care, our goal is to treat the sickest patients first.