Cause they can’t talk in the sense of being able to have a conversation and articulate their thoughts. All they do is mimic human sounds. All pets make certain sounds to convey when they want food and stuff, parrots just mimic the same sound humans make.

Gorillas, on the other hand, have been known to show humanlike intelligence in communicating through sign language

They’re basically organic AI

Maybe because they don’t possess a threat to us despite being surprisingly intelligent(this fact relates more to bigger parrots).