However, I discovered recently that, despite popular belief, there is no law, or even official guidance, against using toilet roll insides. Schools may have their own rules, but there is no sense in which there is some kind of blanket ban. On the contrary, according the the Health and Safety Executive (who are unfairly blamed for a lot of nonsense): "as long as egg boxes and toilet roll centres look clean, there is no reason why they should not be used."
Great! So we can stop beating around the bush and tell people to use toilet rolls again!
Except... no, we can't. If we did, people buying the book would think, 'don't they know you're not allowed to do that?' It would look bad, like we were out of the ark.
We could put an explanation, but depending on the context that might be a bit OTT. And even if the club leaders are convinced, some parents will be horrified if their children come home with crafts made of toilet roll insides.
So we continue to speak vaguely of 'cardboard rolls', and because the myth is unchallenged, it continues...