Not sure why you think this. I work for a major organization and we have made sure to pay close attention to the outcomes of behavioral interviews when we evaluate candidates from Facebook, as we do from other organization with major reputational/ethical stains. Colleagues I speak to are increasingly doing this as well.
So you don't pay attention to behavioral interviews from companies you like? What do you think FB alumni would say during one of these interviews?
"Yeah, my favorite off-site was that time we ritually sacrificed infants to the flaming icon of Moloch. Lots of fun and smelled great! Does your company do off-sites?"
Have you ever actually interviewed someone from FB?
Or is all this about just filtering candidates for people who match your personal political views about, say, the role of advertising in society?
