Who Left the Fridge Open?

I hit the grocery store this afternoon. Many of the aisles had cooler chests: pop, deli meats, fresh pasta. The dairy cases are open but keep the milk a fraction above freezing. The meat packages are laid out in a flat open top case. Up front at the checkout, cashiers are asking "do you want a bag?" in the hopes that you will not take a plastic bag-- but carry out your arm-load of food; or use one the environmentally dubious re-useable bags. If we're worrying about the planet and demonizing plastic bags, why are we leaving the refrigerators open 24x7? Glass doors could keep the cold in, reduce power consumption and people can still see the milk.
So I have to ask why in this environmentally spastic society: why are we not asking why grocers have door-less fridges for the purpose of marketing?