>>283086845
For starters it's fiction and whatever is most fun or resonates with the audience is best. Also they're authors, not anthropologists with a background in world history. This sort of thing is everywhere and was even more frequent before the internet. People generally have a very ethnocentric viewpoint with no concepts of anachronisms until they grow up and learn otherwise.

Try explaining to the average person there were no tomatoes or potatoes in Europe in the middle ages, mutton wasn't commonly eaten on giant cartoonish bones and rather pork was the most common meat, beer was healthier than water, and that most people ate bread of which there was an endless amount of types and was also to a great extent synonymous with both plates and gruel because thats what you do with stale bread. Also the cake and pastries the wealthy ate were likely much less consistent and luxurious than our modern storebought ones, besides in areas known for their culinary prowess, which was due to grain refining and flour production being much less standardized in the past.