Maybe it is because they are always working hard at collecting food. They are very singular of purpose so anything that does not involve finding and collecting food they for the most part ignore. Including humans and their cameras. It is easy to see how hard the bee in the photo above is working. Notice all of the white dots on the bees head and legs? This is pollen that it has inadvertently picked up while collecting food. When it moves to another flower some of the pollen will fall off and pollinate the other plant. This is how most of the plant life on the planet reproduces.