My car was too cheap to have an electric liftgate, though I don’t know if I can open it with a dead battery - never tried, and never had a battery so dead it needed replacing that urgently. Very possible it doesn’t open with a dead battery though, at least if the vehicle is locked when the battery dies.
Costco is the only place I don’t always return carts, since around here the cart returns can get very far away, but curbs you can tuck them away on are everywhere. That, and they have staff just for gathering carts constantly.