On the one per person; it isn’t great, but there is the whole component shortage going on…
One Pi Zero per order long predates the current component shortage. It was true at announcement in 2015. And it wasn't just a "shortage until production ramps up" thing either. It's *always* been true. There has never been a time when you could simply order 100 Pi Zeros at the advertised $5 each.
Contrast that with, say, the Longan Nano, available for $4.80 from China or $6.13 from Mouser:
https://www.mouser.com/ProductDetail/Seeed-Studio/102991302?qs=RcG8xmE7yp15ihBCpLOGNg%3D%3DRight now it says 276 in stock. If you want you can order all 276 and they'll say "Thank you very much for your custom".
Mouser carry Raspberry Pi. They have a lot of Pi 3B, Pi 3+. and Pi 4 in varying RAM sizes:
https://www.mouser.com/c/embedded-solutions/computing/single-board-computers/?m=Raspberry%20PiSadly, they don't seem to have any *stock* at the moment (global component crisis etc). But if you want 100 or 500 Pi4 8 GB they'll be very happy to take your order now and deliver them when they get them on December 20th.
They *don't* have Pi Zero. Never have.
The obvious and surely correct reason is that the Pi Zero at $5 is being sold at a loss. It's not a commercial product. It's charity. The Raspberry Pi Foundation is *explicitly* a charity, not a business.