WC pays based on the location of treatment. So if the accident happened in State A, but the treatment took place in State B, then it would be the rules of State B that would apply. Some states have mandatory fee schedules, some have specific guidelines (percentages and so forth), and other (like mine) are the unfortunate ones without any statutes or fee schedules so we get paid UCR. Since you can't balance bill the patient, you're stuck with what you get, unless payment arrangements are made with the payer.
One noteworthy piece of information, sometimes WC payers will access and use the payment schedule of a contracted company (contracted with the facility) and try to get a discount like that. We have it happen all the time where they go through a contracted network, and if the contracted rate is too high, they pay what they want to anyway (in a UCR situation). The only way we ever get paid the proper network amount is by going through our contacts at whichever network is being utilized and they force the WC payer to pay properly.
If your state has a fee schedule or otherwise, I envy you.