You’re right, A New Hope pretty clearly implies Anakin was originally from Tatooine. The problem is that A New Hope was written under the assumption that Anakin and Vader were separate characters. When George Lucas wrote that dialogue, he was not thinking that Luke was actually hiding from anything. Luke was just an average farmboy who happened to live where he lived. But by the time Return of the Jedi was written, Luke was now Vader’s son, and was sent to Tatooine as an infant because it was a remote location far from the reach of the Empire. But this change to the backstory implies that Vader/Anakin shouldn’t be from Tatooine, because otherwise sending Luke to hide there comes off as a really bad decision. I mean, there’s a reason that modern “witness protection” programs choose locations completely detached from any former associates of the protected witness, and require a complete identity change.
In my opinion, once Vader and Anakin were merged into a single character, Anakin should no longer be from Tatooine. I’d rather just ignore or reinterpret Obi Wan’s line in A New Hope, rather than have to squirm around coming up with excuses for why anyone would hide Luke on the same planet his father grew up on.
I see where you’re coming from, but I think Anakin being born on Tatooine actually works really well for the story. First off, Obi-Wan’s dialogue with Luke in A New Hope is already filled with half-truths, but not everything he says is a lie. He’s protecting Luke from the harsh reality of his father’s fall, but there’s still truth in his words. If we change where Anakin was born, it could make Obi-Wan seem even more deceptive, which I think would undermine his role as a mentor. Keeping Tatooine as Anakin’s birthplace helps maintain a level of trust in what Obi-Wan is telling Luke. Plus, there’s something poetic about both Anakin and Luke starting their journeys on the same desert planet. It creates a strong narrative symmetry that ties their stories together. Anakin’s life starts on Tatooine, and so does Luke’s. This makes Luke’s journey more poignant because he’s unknowingly retracing his father’s steps, only to find his own path in the end.
Now, hiding Luke on Tatooine might seem risky at first — after all, it’s the same planet where Anakin was born — but that’s what makes it so clever. Anakin had such a rough time on Tatooine — being a slave, leaving his mother behind, and eventually losing her — that he’d have no desire to go back. The trauma he experienced there creates a psychological barrier, which makes Tatooine the last place he’d want to revisit. In that sense, it’s actually the perfect place to hide Luke because it plays on Anakin’s deepest pain and memories, keeping him away. So, even though the decision of hiding Luke on Tatooine might seem nonsensical at first, it works perfectly if you introduce a trauma that caused Anakin to not want to return to the planet, which is exactly what Attack of the Clones does. Also, you don’t have to forget that, sometimes, the best place to hide something is in plain sight.