A hand-wavy explanation would be that photons are both particles and waves, so different rules apply. When you create waves on a water surface with your hands,

A hand-wavy explanation would be that photons are both particles and waves, so different rules apply. When you create waves on a water surface with your hands, the speed in which they propagate along the surface is the same regardless of whether you just tap the water straight down, or make a sweep with your hand.