Here is a sentence that starts out to say one thing and ends up saying something completely different:
If you’re using the hold-open latch, you can’t just wander away. That’s what we want to say here.
“Persons using dispensers with hold-open latches must remain at the refueling point during refueling” says it.
So what is “It is unlawful for” doing at the beginning of the sentence? It would be possible to begin the sentence that way, but the rest of the sentence would have to tell us what is unlawful, not what we must do: “It is unlawful for persons using dispensers with hold-open latches to leave the refueling point during refueling” would do it.
The Editor suspects that, for many people, phrases like “it is unlawful” do not mean the sum of their words. Instead, they are symbols that establish a mood. Here, what the writer was thinking was “Warning.” He might just as easily have used an upraised-hand icon or an exclamation point in a triangle, but he didn’t have those on his keyboard, so he typed “IT IS UNLAWFUL FOR” to add a certain atmosphere of warninginess at the beginning. (The Editor might have believed it was a simple mistake, except that this warning was laboriously cut out, laminated, and stuck on every pump in a large gas station near an Interstate exit. There were many opportunities to notice a typing mistake.)
Words do have meanings, and the best way to avoid misleading your readers is to be aware of the meaning of every word you write. Never accept set phrases as set.
By the way, give credit to the writer for the apology. The rule is there for a reason, but it is always good to apologize when you find yourself forced to tell people they can’t do something.