Because they can't
I was looking for a gift for my in-laws (who have everything). I was looking in the gadgets section of Marshall Fields, since they have a Marshall Fields in Savannah. They have a paperweight in the gadgets section. It looks like a garden stepping stone, and says,
"If tears could build a stairway
And memories, a lane
I'd walk right up to heaven
And bring you home again"

I read it and started bawling all over my keyboard.