Perhaps you could take a photo of shuttered US factories as the manufacturing of goods moves to China....so Walmart can offer such low prices....or a line of attorneys ...defending Walmart against the many employment lawsuits...or Walmart employees getting government medical coverage instead of company medical ... all so they can offer low prices....

but of course...if you are indifferent....does Walmart ever close? IF so, you could take a photo of the building with no cars or people around.....

p.s. most stores and malls have no photo policies....to protect themselves against people planning buglaries...I would get permission before photographing inside.