Paulk

Lots of things Lucas does don't quite align, but something that really does not get nearly enough attention virtually anywhere in discussions about SW is Lucas's them about the disrespect and objectification of androids. It was a slight, but significant theme in the OT, but he goes out of his way to emphasize it again in TPM—comparing how Padme respects and honors R2. Outer Rim and remote territories (like Tatooine) fundamentally do not. He clearly considers it a slave culture. But while even some enslavers might develop closer relationships with their slaves, many, if not most, don't register them as "beings" at all.

It should not be surprising, then, that Owen wouldn't think about C-3PO at all or even remember his name. They've probably had dozens of droids over the 20+ years since he's been gone, and except for this 1 minute exchange, he might not engage with him at all. Less convincing, though, might be that he wouldn't necessarily remember having had a protocol droid that worked on the farm once. But then again, once having had a protocol droid (that looked different than his last one) that did some work on the farm briefly for the long dead wife of his father really places a lot more importance on the value of these "slaves" than he likely felt.

It's fair to suggest that Lucas maybe didn't think about the potential contradiction he introduced here, but I think he'd have a thematically consistent point that still fits.