From what I understand, Salvage (strictly talking Box D stuff - not Box C CRC) items are not always sorted through, but the Central Returns Center (CRC) audits things randomly to ensure that nothing bad is getting sent, mostly empty packages, non-Salvageable items like food or medicine, so the labels exist for the purpose of those random audits.
CRC stuff (which is silly why it’s called that, as it all goes to the CRC) like electronics, furniture, etc. is strictly processed piece by piece. That’s because a lot of that stuff (like Apple products) are shipped back to the manufacturer for credit back, or also sent forward for the next part.
After all is said and done, (a) Salvage and (b) non-creditable CRC is palletized and sent off to a clearance warehouse where it’s auctioned off in pallets to the next highest bidder like Dirt Cheap, ROSS, and your other local discount stores.
Some of it does end up in thrift stores via the CRC donating things they leave out of pallets, but who knows.