> my hungry teenager looks in the pantry and the refrigerator and says, "all we have is ingredients"

Matches my experience. I too would contest that reasonable quality food is more expensive. In my experience it's actually somewhat cheaper by any metric except $/calorie and even then you could just add butter or oil to the "healthy" alternative to juice the numbers.

I think the primary differentiator is convenience. Grabbing an actually rather expensive box from the cupboard beats out spending 30 minutes cooking and another 10 cleaning.