No, it’s that it is incredibly rare for someone to actually want to liquidate their account because the reason people do is usually to move banks and that use-case is better served with a cashier’s check. It’s not at all surprising that random branches don’t keep that much cash.

You can always liquidate your account. What you can't do is make it some random branch's problem in a spur-of-the-moment decision; you have to plan it with them.

No, that doesn't follow. You can definitely remove large amounts of cash, you just have to think ahead a little. Also, you have overlooked the fact that for many people a cashier's check is more convenient than a large wad of cash, especially if their sole object is to deposit it at a competing institution.