I asked the same question not too long ago. Everyone agreed that no one has ever asked how old the person is who will eat it. Others said they order the kids menu when they aren't real hungry, or need a low calorie meal. So yeah, I guess we can.
Ya. At quick service how could they have any idea if the food is for you or a child that is waiting at a table with another grown up. Sometime kids meals are as big as a full grown up meals elsewhere.