First of all, why does Luke get sent to the ass-end of the galaxy, Tatooine, and Leia ends up on fancy Alderaan? Just wondering. That aside, if they're afraid Luke MAY be discovered, why hide the kid on ANAKIN'S home planet? With people that Anakin KNOWS pretty darn well. And okay, fine, if I can believe all that, it's no biggie, right?
Well, how about this idea gang - Change his last fucking name! He can be Luke Burgerflipper. Or, hmm, Luke Lars? Just an idea.
Because Vader/Anakin doesn't know his kids are alive, right? Okay, that's fine. But what if he happened to return to Tatooine one day. Maybe wanted to visit his Mama's grave/ash pit. And he just might hear about some punk-ass kid named Luke Skywalker and say, "Hey, wait a sec, that's MY fucking last name. Maybe I should look into this kid."