I believe the ICC and state governments do reach agreements. For example, the Michigan state government's site instructs citizens to go buy the laws from ICC. Fun fact: the only play to read these Michigan laws for free online is UpCodes. We bought the physical books, sliced, scanned, OCRed, ingested and posted them.
In terms of our plan, we're relying a lot on case law. We put 4 very clear examples on our advocacy page. (up.codes/free-law, see "Didn't ICC already litigate this case?" under the FAQ)
> I have a small amount of sympathy for the ICC saying they did work that is now being used without any compensation.
Just don't forget that the codes are written by volunteers who never see a penny AFAIK. ICC organizers the volunteers (which is an important time-consuming task I do recognize).
Also, don't think they have no compensation. The majority of ICC’s revenue comes from program services, including consulting, certification, and training, which do not rely on profiting by limiting access to the law. Their CEO makes $742,000 in salary, which is arguably a bit high for a non-profit.