Ever worked for a big company? Ever partnered with a big IP? All of the above are very possible, and probably. But there is also red tape. Lawyers, licensing, art reviews, approvals, meetings, availability of key people...
But all together, I think the big thing is that a lot of that doesn't get started until the artwork is approved. Which is late in the game relative to when the books are released. Then as said, you have to model it. And get approvals. Then test print is and get approvals. Then have the molds constructed (because printing quantities are cost prohibitive). Then test mold, validate and get approval. Then manufacture a bunch of them. Then you can start to market them and start to distribute and sell them.