That culture has been built up over years. And probably most of the people they hire don't have the life experiences that would give them pause and allow them to consider or even recognize if what they're tasked to do is creepy or not.
Not at FB but just doing enterprise software development I've had to explain to other developers that capturing and storing user info just because we can is in the "not okay" category. There are plenty of people who don't even consider ethics at work. They get a feature request, so they deliver it, with no second thoughts. These aren't bad people per se, it just doesn't occur to them to question the reasons for a request or what the end result is within a larger context.
I think this is because people don't see the value of data. I've also heard a lot of justification about people saying "well my individual data isn't worth anything" but also being freaked out by ads they get. I'm always confused by this juxtaposition. But I guess there's similar stances in a lot of places in our culture right now.
That, or they don't care. Or they don't care enough.
If you do care, you get filtered out.
Theranos is the prime example of this. Whoever, was negative about the product in a way was removed. If one questioned a promise of the product because it was IMPOSSIBLE they got fired.