I’ve worked at both Facebook and Google, and I’d second this sentiment. It is pretty disgusting that anyone with a passable knowledge of how to hide their tracks can basically get all of the information (messages, posts, photos, private information) they want about you. Sure, they might get fired if they’re caught, and maaaaaaaybe (read: probably not) face legal action, but they can do a lot of damage beforehand. And if they’re good enough, they won’t get caught.
I trust the people that I worked with there, but these are big organizations, and a lot more people than I would be comfortable with have essentially administrator access to private data.