Why does peter chao always wear sunglasses?

because he is an actor and he doesn't want anybody know who he is. His real name is Davin Tong and Peter Chao is his character he plays. Its like Sacha Cohen plays as Borat. Try search Davin Tong on YouTube and click the one with the title "That ain't white"

That is the real peter chao and his accent is actually fake.