Eh, idk, using the term "machine learning" gets a lot of attention now too, to the point that it's kind of a buzzword even though it is a legitimate field of study. I think its more that the average non-technical person hears "AI" and "machine learning" and assumes they're the same thing.

Machine learning is still a subset of AI. That being said I think its clear that ML is the most popular subset of AI at the moment, and so when the average person hears of AI they likely think of ML as well, to the point that some people may just use the two terms interchangeably.