Why don't the walls move during the day?

Because open interest, the raw material of dealer positioning, settles overnight rather than intraday. Wall structure shifts day to day. During the session, what evolves is spot, time decay, and volatility, and you can watch those pull on the standing structure.

So a call wall that hasn't moved since the open isn't stuck; that's how positioning works. The read that changes all day long is where price sits relative to the walls and the flip, which is exactly what the levels exist to show.