Sorry, do you actually believe what you wrote?
Let's say it's 9am. My pediatrician's office is open. The urgent care down the road is open. The ER is open. My child has a fever of 105F.
Why on Earth do you think the *real cost* of treating my child at the ER is 10x greater than at my pediatrician's office or the urgent care place? Do you think regular pediatricians make $200k/year, but ER p ediatricians make $2 million/year? Do ER nurses make 10x more salary than regular nurses? Does infant Tylenol cost 10x more when an ER buys it?
If ER is 10x more expensive, that means they are doing cost-sharing between unprofitable and profitable services. A thug with a gunshot wound may cost a lot to treat, and may end up not paying, so they jack up the prices of infant Tylenol to cover for it. It's a poor-man's insurance scheme for doctors... people facing emergencies may not pay, so soak the ones who do pay.
The thing is, if you successfully divert all the people with fevers away from the ER and over to urgent care, that doesn't magically make the ER more cost efficient. It doesn't actually save money. It just gets rid of some of the cost-sharing. So other services that you can't shift get even more expensive.
And if you're simply talking about preventive care making emergencies happen less frequently, studies are inconclusive about whether that actually saves money on average. The cost of preventive care over a 50 year period is more than the ER cost of a single episode.