Endermen don't pick up plant from flower pot

since planting plant from flower pot is the same thing as planting plant on ground, i assume that enderman would pick up the plant from the flower pot or pick up the whole potted plant, but they wouldn't.

to reproduce, make a 3 blocks deep hole with potted cactus, spawn enderman inside that hole, and wait. you'll see that the enderman won't pick up.