My dad was evacuated from Yemen by the military when the civil war there broke out. That blue passport was his ticket out of a country that was rapidly disintegrating. He was not charged anything for that. So they don't always charge you (indeed I've never heard of it).
My dad was evacuated 15-20 years ago. Before that, Yemen was a poor but pretty peaceful country. I think we should evacuate the folks stuck there now, but the state department isn't wrong to say that they've had a lot of notice and shouldn't have been there in the first place.
Didn't know about that situation with US citizens in Yemen, one of the comments posted in response to the LA Times article says Russia ended up evacuating them? Is that true, or just propaganda? The only source is RT..