And, while it might not be rational current-day policy...there is very much a history behind this. For a very quick intro: https://www.britannica.com/topic/opium-trade
When a young country and barely able to wrestle independence, it was feared the British would team up with Scandinavian forces (a large portion of immigrants to North Americas were Scandinavian) while being worn thin by also battling Napoleon. By banning traditional foods such as herring, licorice and even black pudding and haggis, any potential pre-invasion force of saboteurs and partisans would complain about only having hamburgers and bad pizza to eat and thus be discovered.