That one that looks like Habitat for Humanity bugs me. At least the others, you can sort of say these people are "professional tradesman" (used very loosely) responsible for their own well being, but it's pretty much understood that for a lot of Habitat you're just dealing with altruistic desk-jockeys.
So lets put a whole bunch of them on a roof with a 30 degree pitch and no toe-boards, clustered up in a tight little group of nail guns and hammers. And the folks that aren't on the roof? Let's have them play around a metal scaffold right next to the un-guarded temporary service drop.
I mean, come on, at least somebody could be making an attempt at safety.
-John