> The major thing I can think of is higher volume for the Pi foundation, which means more negotiating power with their chip suppliers or price breaks at a certain ordering volume.

Normally you'd be right. But apparently (the unsubstantiated rumor is that) Broadcom is pissed that RPi built a for profit company on top of the IP licenses Broadcom thought they were donating to a nonprofit and is stone walling RPi wrt getting larger orders than previously negotiated or working with them on an RPi5 and that's the major issue with the continuing stocking issues.