However, the same could not be said for R2-D2, who never had his memories erased. While there isn't a canonical reason for this decision, the likely explanation may have been that Threepio was more likely to say something he shouldn't have.
Anakin Skywalker ignored this procedure in regards to R2-D2, to the chagrin of both the Jedi Council and the Republic Military leadership. The Galactic Empire did not grant its droids any independence and sought to keep them subservient and docile.
A smart, spunky droid who would serve a multitude of masters over his lifetime, R2-D2 was never given a full memory wipe nor did he ever receive new programming, with these factors resulting in an adventurous and independent attitude.
C-3PO had his memories wiped after Episode III, but R2-D2 did not. However, they were working together on the same ship afterwards, where presumably, they would have conversations.
C-3PO had his memory banks deleted in Ep. 3 Revenge of the Sith and again in the Rise of Skywalker. In Ep. 9, the C-3PO's memory got deleted again when the droid tech overrode his fail safe which forbid him to translate ancient Sith.
Did R2-D2 and C-3PO have their memories wiped in episode 3?
The two droids were dumped back on the streets, their memories wiped of the incident. Unlike R2-D2, Threepio's mind is wiped of all memories after the birth of Luke and Leia. Senator Bail Organa assigns C-3PO to duty aboard an Alderaanian diplomatic cruiser, serving under Captain Antilles.
secondly, in Legends, R2 was given programming that actually restricted him. from sharing any information with Luke or Leia. about their parents or relation to one another. this was all part of the plan. to conceal this information from the twins.
Obi-wan responds to starwars.wikia.com/wiki/Luke_Skywalker saying R2 belongs to him with, “I don't seem to remember ever owning a droid,” which is technically true, because Obi-Wan never did “own” R2 or C-3PO. Obi-Wan then makes a comment that suggests he's more than aware of R2's impressive capabilities.
Darth Vader's true identity as Anakin Skywalker was a highly guarded secret, known only to a select few individuals including Palpatine, Obi-Wan Kenobi, Luke, Han, Leia, R2-D2, C-3PO, Master Yoda, Bail Organa, Ahsoka Tano, Darth Maul, Grand Moff Tarkin, Grand Admiral Thrawn, Jocasta Nu, Ferren Barr, Verla, Reva, ...
Darth Vader acts like he doesn't even know C-3PO or R2D2. They were with him since he was a child. He did everything he could to forget his past. Also, his plating had been replaced many times, and protocol droids all look very similar.
Because he never owned a droid. R2-D2 was owned by Padme and later Anakin, and after that Bail Organa. R4-P17 was assigned to him to assist, not given to him to own. So he really never owned one.
By wiping his memory, it allowed the leeway necessary to bridge the logic gap created by the previous two prequel films. However, the same could not be said for R2-D2, who never had his memories erased.
At the end of Star Wars: Episode III - Revenge of the Sith, C-3PO's memory was wiped, allowing him a fresh start by the time A New Hope begins, but R2-D2's memories remained intact, which is why many fans wonder why he didn't tell Luke the truth about his family history, but he might have not done that because he didn' ...
Although C-3PO is a tell-all, it's possible that he was directly programmed not to say who Leia is. This is something that George Lucas himself suggested in an interview back in the 1970s, which made it into the book The Making of Star Wars: The Definitive Story Behind the Original Film.
As has been noted in several instances, Artoo has never had a full memory wipe, enabling him to retain his recollections of everything he saw and heard over the decades. This includes his first meeting with Padme Amidala, a nine-year-old Anakin Skywalker, and C-3PO himself during the events of The Phantom Menace.
Following Padmé's death, C-3PO became the property of Bail Organa, who also adopted Leia, and due to C-3PO's tendency to talk a lot (and also for safety reasons as he knew too much about Luke and Leia), Organa arranged for the droid to receive a memory wipe.
Because as far as he knows it's just a generic protocol droid. There are millions of them all over the galaxy. He has no reason to think this droid is the same one he was briefly acquainted with many years ago.
Bail's final line of the film and instruction to the Captain, says “…have the Protocol droid's mind wiped.” Because Bail Organa had them wipe his memory at the end of Revenge Of The Sith and he never came back to Tatooine until A New Hope.
in the Dark Horse comic series star Wars Tales, which is now part of legends, it's revealed that Darth Vader did recognize C. 3PO on Cloud City. when 3PO was shot by Stormtroopers, his parts were brought before Vader. because the Imperials thought he could hold valuable.
He didn't recognize him because again, they all look the same & it was decades until he saw him again. There was no reason to believe he or R2 even existed anymore.
In Star Wars: The Force Awakens, set approximately 30 years after Return of the Jedi, R2-D2 is revealed to be kept in storage at the Resistance base on the planet D'Qar, having put himself in a low-power mode after Luke Skywalker's disappearance.
