"For sale: baby shoes, never worn."
Which is to say, I think that her take makes this even more apt response... the people getting sad about this have never tried to put a rover on the moon.
They're often gifted by family to the expecting parents and sometimes kept as a keepsake, so someone getting rid of never-worn booties works a little better. Though it's typically considered distasteful to sell handmade gifts.
Of course, the sentence seems to work fine as a story regardless of its correctness, based on its enduring popularity.