AUTO a/c head & foot mode??

This is driving me nuts... Does anyone have a good answer as to why I can't run my air conditioning on AUTO with the mode in head and foot (opposed to only head). I feel like Toyota needs to release a software update for this bs. Is there something obvious I am missing?

 

i guess the idea behind this is that when putting AC on auto its job is to maintain a set temperature not just blast air everywhere. cold air is heavier then hot so the cold air drops to the bottom and your hot air in the vehicle rise to the top. using only the top vents help keeping the temperature throughout the vehicle at a pretty close proximity.