I have actually written some software for keeping track of pallets. This was about 6 years ago. There was about 10K wooden pallets and 90K plastic crates to keep track of. We also had CHEP pallets. These had to be tracked separately and manually updated on CHEPs IE only website with no API. No RFIDs were involved. The system required two manual counts. One on pick up and another on delivery. If the two counts were way off, or one end was missing, the shipment would be flagged. It kind of worked.