Of course there is no way to know what is not shown in that photo. If they were facing an allied advance moving from left to right (direction of US armour and troops in the photo) and that ditch stays open to their left, then it was a poor choice of positions on the part of the German Panzerschreck team. The converse of that would mostly be true if they were expecting the advance from the right. Assuming that they were hit from the left in that photo and if no barrier exists that we can't see then anything could/would have rolled them up to include one guy with a Garand and a full clip. Anyway, we will likely never know what happened or what was there that we can't see but the photo makes the case for why cover and concealment are important.