It's a very common thing to put a made up one way street into the map. If your competitor has the same street then it's pretty easy to tell they are "using" your map data.
Cisco allegedly did something similar when it suspected Huwei was usign it's source code. They added some minor typos to error messages and then check the Huawei routers and sure enough they had the same mis-spellings.
Since no one programs against the textual strings of the error messages, they jumped to the conclusion it was source code theft and not a clean room implementation that Huawei was using
Land surveyor and cartographer here. I just came by to say that while "traps" are common on land maps, in nautical cartography they are not. I don't understand why anybody would reasonably surmise that this is a "trap island" since marine cartographers do not use them.
The full quote from the article covers your concern.
> "A spokesman from the service told Australian newspapers that while some map makers intentionally include phantom streets to prevent copyright infringements, that was was not usually the case with nautical charts because it would reduce confidence in them."
It doesn't prevent copyright infringement, so much as be able to detect copyright infringment after the fact. They are called 'trap streets'. They aren't just streets, but kinks in roads or rivers, churchs that aren't there.
This way, if someone copies your map, you can prove they copied you. If your map was totally accurate, then they (the copier) could claim that they went out into the world and surveyed it. If they include your trap street that only exists on your map, and not reality, then it must be a copy.
Its actually more devious than that. Facts are not copyrightable since they are not creative works; locations of streets and phone number listings are both not copyrightable. On the other hand, fictional streets or phone numbers are copyrightable so if someone copies a trap street they are infringing when they otherwise wouldn't be if the map was accurate.
Melway is a company that makes excellent street directories for all the major cities in Australia. It came out a while ago that on every single page, there are intentional errors that would help catch someone copying their maps. There was a phone box marked on my street that didn't exist, and a friend's house was next to a street that didn't exist.
It gained some attention a while back because it could turn into a safety issue - i.e. I rely on the map to tell me where I can find a phone box to call emergency services. They downplayed it.
It's entirely likely that it's just outdated data. However, it's not so much a part of a trend of disappearing phone booths, TUSMA is providing government money to Telstra for keeping about 20,000 phone booths active such that all Australians have reasonable access to one.
I checked the local Ausway map on street-directory.com.au and the phone booth that's on there is actually there, so based on a massive set of two data points and some intuitising in applying typical rates of intentional mistakes applicable to other data, like streets, it's probably only a few phone booths that are intentional mistakes.