Actually, it turns out that during World War I, bombing enemy targets was basically like playing darts with explosives, because the bombs had to be aimed and dropped by hand. Correction: a badly shaking and sweating hand.
However, that's not exactly what's happening in that picture, because that picture wasn't taken on an airplane. It was taken on a SSZ-class blimp, a setup so desperately primitive it was essentially a boat dangling beneath a giant balloon.
Early Aviation Image Archive
They were supposed to kill people, but they kept going on whimsical adventures instead.
A small team of soldiers could sit inside this airborne canoe as it spit in the face of God and drop satchels of bombs on the populace below like a bunch of disgruntled Christmas elves, because as this article demonstrates, old-timey war frequently set the benchmark for unintentional comedy.