But laws can't do that in infinite detail. It's literally impossible. So it's not a straw man at all -- that was my point.
At some point, regulatory agencies, like anything in the executive branch, have to decide for themselves how to get their job done. Because they have to do that a million times every day.
If Congress didn't specify who will pay for the observers, it makes much more sense to leave it up to the agency than to the courts, except in cases of obvious abuse, corruption, etc. -- which this does not appear to be.
I agree it sucks that the fishing vessels have to pay for the observers, but it seems obvious to me that the body to fix that is Congress. If the fishing industry can't get the agency to change it, then they should be contacting their Congressional representatives to change it. And Congress either will or won't, but that's literally who is in charge of this.
It seems like a strange issue for the courts to get involved with, because there's no conflict with other laws or with the constitution.