Because they care? I know it's a shocking concept, but people actually care. "Big corporations" aren't some amorphous number crunching machine. They're staffed

Because they care? I know it's a shocking concept, but people actually care. "Big corporations" aren't some amorphous number crunching machine. They're staffed by people, and those people have concerns, and priorities, and principles. When you specifically hire for people who share those principles, and announce them loudly as part of your culture, people actually can, and do, get upset, and demand change when you don't act accordingly — and change can and does happen.