I buy used Festools often, and keep some for myself and sell others again after refurbishing. Most come with cords because sellers know the tool is worth more that way.
It does happen quite often that we see brand new tools without cords, systainers or other accessories, and many times I suspect they were stolen from a store display. Sometimes they come from a bankruptcy sale because the auctioneer simply yanks the lots off the shelves without trying to match the accessories. Unless it is very obvious they have a legitimate source, I stay far away from those deals.
One explanation for missing cords could be that the Plug-It cords break easily. When you have multiple Festools, you might not find the need to replace a cord immediately, using one from another tool instead. At least I don't, those buggers are expensive. When it becomes time to say goodbye to a tool, sellers might opt to sell it without the cord so the tools they keep still have them. Not the best thing to do, I think, buyers will know they have to add the cost of the cord to the tool, and won't like it.