Thats what Apple wants you to think. In reality it has nothing to do with privacy. Apple could let 3rd parties tap into these APIs but only after the user clicks away a big scary message telling the user they are leaving the comfort of the apple curated garden.

This allows competition, but also allows privacy for those who want it. See? Simple really, but Apple being Apple dont want to let 3rd parties use its AI APIs and so we have this standoff.