$300 for a splint is one thing. Try negotiating an MRI when you've just been in a car accident.
Its a real problem. Insurance companies have a ton of weight by virtue of representing many patients, which they effectively leverage for lower prices. Those paying out of pocket have no such leverage, and pay much more.
She has negotiated for post-hoc price reductions on emergency care.
Hospitals have leeway in what they charge. If you make it clear that you will be a pain in the ass unless they give you a good deal, they will do so. This is where you drop words like bankruptcy, $25/month for 30 years payment plans, and threaten to contest every single item (out of 47) on the bill. They will take all sorts of nickel&dime charges off your bill, lower prices here and there, etc, giving you a reasonable deal.
All this aggressive price negotiation is fine if that is your choice. But keep in mind your company will have to employ other people and if the company does not provide health insurance you will be expecting your employees to also perform these same kinds of price negotiations for their medical services.
Much like vaccination, this only works because many other people are covered by insurance. What the hospital doesn't charge you (and thousands of other people without insurance), they make up for by raising rates across the board. Just because you negotiated the rate downward doesn't mean the procedure's cost went down for the hospital.
Its a real problem. Insurance companies have a ton of weight by virtue of representing many patients, which they effectively leverage for lower prices. Those paying out of pocket have no such leverage, and pay much more.