Vehicles being transported, unfortunately, cannot be used as mini moving pods. The primary reason is that only the vehicle itself is covered by insurance during transport. Drivers need to eat and sleep, so the truck is not manned 24/7. Anything inside the vehicle during transit just invites vandalism.
In addition, diesel prices are high and carriers are very mindful of any additional weight. Not only that, but calculations for their loads are based on empty vehicles. Extra items can put them over their maximum weight allowed by law, producing hefty fines for the carrier.