Specifically for those companies, probably not. But it could also be an obscure feature, or simply a bug that FB's famously clever and eager-to-help engineers

Specifically for those companies, probably not. But it could also be an obscure feature, or simply a bug that FB's famously clever and eager-to-help engineers found a way to exploit. It wouldn't surprise me at all. Recall that Mark himself has acknowledged that he tapes over his laptops' camera holes when they're theoretically not in use. Why? Because he knows what's up.