It's not a technical shell game. If you asked your mom, "hey, do you think they meant to have people be able to access those documents, where you can only get to them by editing numbers in the URL," she would say "no." That's what defines what is legal or not in this context.
https://www.google.com/search?q=robodialer\
If you asked your mom, "Am I free to access all the public-facing information on the Government Freedom of Information server", what would she say? The technical details of how to make the connection are irrelevant. My mother doesn't know how to connect to a BBS, does that mean that anyone accessing a BBS is breaking the law?
No, she would say "I don't know what you're talking about, can you put that in plain English?" And then you could get her to give any answer you wanted by phrasing the plain English appropriately.
Good thing computers use unambiguous protocols to communicate explicit intent.
> If you asked your mom, [...] That's what defines what is legal or not in this context.
I'm really terrified of a world where the law is made by asking laypeople what they think. Just like we don't define borders by asking random strangers on the street where countries are, I don't see how it's a good idea to define laws for technical services and protocols by asking people who barely understand computers what they think.