The difference is that photos were originally intended to be printed and possibly displayed in a frame, placed on a table or hung on a wall. These frames can be in either orientation.

Do you watch your television vertically as well? Is the letterboxing in movies on the sides or the top and bottom?

Exactly. We can't trust these people to make informed video decisions. For the good of everyone we need to take away their ability to easily shoot vertical video. Only then will this epidemic stop.