The SQL planner is most definitely "AI", we're just so used to it that it's become trite to say so. I'm having trouble tracking down the version I heard about, but this essentially the "AI effect": "Every time we figure out how to do one of these tings, it ceases to be called AI and just becomes useful software" [0].
Part of the reason I'm dismissive of the current pushback against AI is that people have such a vague definition of it that it starts becoming all inclusive to subsume things like SQL, the Shazam algorithm, etc. Personally, I think it's a good reminder that SQL has quite a bit of intelligence in it. After all, SQL was one of the first mass successes of a declarative based engine.
Put another way, in some abstract sense, one of the differences between SQL query planning and an LLM is one of scale and compute. I wouldn't be surprised that, at some point in the future, we'll see LLM simulation in SQL(ite) akin to how people use different systems to run Doom.