That, actually, is not my invention.
Basically, bread was regulated in terms of size, ingredients, &c, a sensible standardisation considering how it was a staple food during the era. But bakers, being humans and thus just as prone to trickery in pursuit of gain as everyone else, found ways to cheat the rules. They'd done everything from putting sawdust in the flour, using measuring boards with a hole in them where the dough would fall through and thus make the finished bread smaller, all sorts of crazy stuff.
Incidentally, this is why we have the baker's dozen. Bakers eager to prove themselves honest gave an extra loaf to the dozen, as a gesture of how definitely not-greedy they are.
History, amirite? Sometimes even funnier than what fiction can think up.
Mutatis mutandis. Si non confectus, non reficiat.