Maybe part of it is energy efficiency. For humans, being idle doesn't save all that many calories compared to how much we burn anyway to keep our body temperatu

Maybe part of it is energy efficiency. For humans, being idle doesn't save all that many calories compared to how much we burn anyway to keep our body temperature constant. That's probably different for ants, and thus, when individual ants are not running around without purpose, the whole colony can get by with less food.