Does it? SpaceX doesn't publish official numbers, but nextspaceflight.com has the Falcon 9 at 99.5% success rate, which seems a bit better than "keeps failing" to me.
The Raptor v3 had a 7% (3/39) failure rate on yesterday's Starship Flight 14. As others have mentioned, Falcon 9 uses the Merlin engine, which is a completely different, much lower complexity engine.
I actually agree with your point overall, but Falcon 9 uses the Merlin, not the newer raptor 3 for starship which is more 3d printing and has had some teething issues (no definite causation, and I expect they’ll get it sorted).
https://nextspaceflight.com/rockets/3/