Don't forget that IATA DGR manual states that every passenger is allowed to bring 2 kg of dry ice as handluggage ir checked bags.
If a cargo shipper wants to send 1 kg of dry ice to cool something down - its dangerous goods. If the dry ice is used to keep food cool in the pantry it isn't, but at least the quantity is known to the airline. But each passenger can bring 2 kg.....
/fs