Yeah, R2-D2 is very unusual though in that he's one of a handful of droids that haven't been wiped over the years, which makes him the only character to witness and remember every major event that began with the Invasion of Naboo (Phantom Menace), right up to the beginning of the war with the First Order (Force Awakens), which makes it a 66 year timeframe.
@Sitnspin, armour tends to be useless when you have people with blasters and against all luck; run into someone thats wielding the intergalactic version of Ron Swanson's "I can do what I want permit" in the form of a lightsaber. Seriously, the lightsaber is a better form of protection than most armour within the setting.
And with regards to sapience or sentience, this is taken from canon sources.
"Sentience was the ability of an organic species to think intelligently. Sentient species notably included the Ewoks, the Patitites, the Gungans, and the Geonosians. Non-sentient organics of the animal kingdom were variously referred to as "creatures" or "beasts." There also existed creatures that appeared to have emerging sentience, such as the Zillo Beast.
Under the laws of the Galactic Republic, sentient beings could not be used as slaves. However, slavery thrived on certain remote planets such as Tatooine, and was considered a profitable trade among the Zygerrians. Most droids were afforded programming that did not allow them to harm sentient beings, with notable exceptions such as police droids and battle droids."
Its more of an in-universe distinction.
Yes, sapience is the correct term here on earth, but Star Wars draws from a long tradition in SF of using the term "sentient," which dates back to a time when it was thought that only intelligent beings (i.e. humans) actually felt things (other pop SF such as Star Trek and Transformers also use this term). Bear in mind that Star Wars took a lot of inspiration from the old Flash Gordon serials and the like, so a lot of the terminology is outdated or just plain wrong.
But at the same time, I try to fall back onto that classic MST3K mantra of trying to relax, its only a movie. Its going to be wrong in some instances or plain preposterous in others, but in the end, it doesn't matter. Its people running around in costumes, making pewpewpew noises with James Earl Jones sits to one side drinking tea and sounding menacing.
