I may be wrong, but the impression I'm getting is that people are offended that facebook have used the photos that have people tagged them in as data for training their facial recognition software without them agreeing to it.

It's the fact that they now have the power to determine whether you're in a photo, any photo, or even any video, anywhere in the world, that has people worried. What might facebook end up doing with that?

Of course there was nothing stopping them doing this without it being obvious to anyone.