So... the system works like this:

I have a hospital. I take insurance. I take medicaid. I take medicare. I take cash. In order to take everything but cash, me and the insurance companies (including those who administer medicare and medicaid because contrary to popular opinion, there are firms responsible for managing these plans for the government) have agreements as to what they will pay me for what services.

Unless I'm explicitly required to disclose what those rates are (and in WA state, at least, they're explicitly required to disclose), the insurance companies can compel providers to secrecy. For that matter, providers have no particular reason to disclose either.

When it comes time to get paid, the provider sends a bill to the insurance company. Typically you ask for everything under the sun. You charge as much as humanly possible. There will be things that you expect to get paid for that you don't, and things you don't expect to get paid for that you do. This is because the people doing medical billing at the insurance companies took a 30 day course, have no applicable skill, are going to stop doing medical billing soon and have no real experience with what the fuck they're doing. This is by design. The insurance companies do not want to pay. The job is basically one of matching up billing codes as inefficiently as possible; the entire profession could be eliminated with a not-very-clever package of code between the providers Electronic Health Record and the insurer's billing department but that doesn't make the insurance company money.

So okay. We wait 90 days (typically; the birth center got paid last week for stuff we billed in early 2018) and whatever the insurance company kicks back, the hospital dumps on the patient. So for example, if the hospital decided to bill $400 for a blood draw but the insurer only wanted to pay $25, the patient pays... NOPE! not $375, $0 because part of the contract is that the hospital has to take what the insurer says they'll pay because of that contract. But if the insurer decides that a blood draw isn't covered in this instance, then the hospital will bill the patient... that's right! $400! even though they only had an expectation of $25.

Here's the thing. The hospital knew they probably weren't going to get $400. They probably were going to get $25 except there's some idiot munchkin on his first day who decides that based on his ouija board blood draws aren't covered under a waning gibbous moon. But now the patient is going to be sent to collections over a test he didn't know he needed and his doctor thought would be covered. And collections will pay $12 for that $400 bill and proceed to ruin the patient's life because collections agents are scum sucking villains.

And now everyone's mad at the hospital.

So theoretically, under this law you get to see that the hospital only ever expected to get $25 so if they're going to bill you, they need to bill you for $25, not $400, except there's nothing in the law that says they have to bill you what the insurance said they'd bill you, and as just explained, a fee of $300 a day is less than the money they get if one person doesn't want to be sent to collections over an overpriced blood draw so why the fuck would they ever disclose?

The law would theoretically apply to 600 hospitals. 600 hospitals times 300 bucks is $180k a day or about $5400 a month which is not quite enough to cover the rent of the office for a single lobbyist to cry a river about this. The end result will be the Trump administration saying "we tried to help you guys but the hospitals! They're heartless!" and monsters like HCA (which runs fully a third of the hospitals in the US) will look at the ones that are struggling and observe that $300 a day decreases their profitability a tiny amount and those will be the first to go and suddenly there's only 580 hospitals the rule applies to and we call that capitalism.