Trading unfairly has apparently only just become illegal

I noticed this story on the BBC website: a judge has told a father and son business that they would be fined or jailed if they continued to bully or threaten elderly customers. What surprised me was that the law which makes their behaviour illegal only came into force on 26 May! I would have thought that businesses were automatically under an obligation not to trade unfairly, without needing a court order to tell them so.