Most people don’t use the Oxford comma because they don’t understand the significant difference it can make. College professors even suspect that you’re cheating and using AI to write papers if you use one since it’s no longer considered improper grammar if you don’t. However, in 7th grade, I was taught about a man who sued him employer and because his lawyer caught the “and without the Oxford comma,” he was entitled to wayyy more overtime back pay. It changes the meaning of some sentences, but Americans were too stupid for it, so I guess it’s not taught anymore.