Not all dimensional lumber is completely dry, which is why it warps and potentially splits. There are three ratings: GRN for having an excess of 19% moisture at the time of surfacing, KILN or KD for no more than 19%, and MC15/KD15 which has no more than 15%.

This is not necessarily common knowledge either.

Anecdotally, I have bought soaking wet wood from Home Depot before. It sucked because by the time it was dry enough to use, every single board was as crooked as a politician looking to get reelected.