Anyone who's spent time around horses has had their foot stepped on and farriers spend most of their time vulnerable. The worst part is it's not like them walking by and stepping on you, usually they are changing position and stand on your foot, so you can't do anything until you convince them to move.
I see the heavy shoe still has one caulk(or cork, depending on where you're from), but none left, or never were, on the smaller shoe.