i hire junior devs directly out of school, because that's the only place where i get unbiased and trainable people.

that said, i think bias peaks after a few years, after that, people get more and more experience that helps them keep their bias in check.

i was like that. i had a strong bias against programming languages that i didn't know anything about. it was prejudice, pure and simple. but as i learned more and more, i realized the errors of my ways, and bias was replaced by experience.