>though as I type this I realise they may have worded it to encapsulate only honest mistakes rather than people trying deliberately to break the system

Exactly. Retailers generally assume liability for honest mistakes made by their system/employees and sometimes even their customers. However, when people knowingly exploit a loophole for financial gain it becomes fraud. Here's a real example - https://www.wfmynews2.com/article/news/local/greensboro-woma...