It’s because of the middleman trade that has sprung up.
Go to Wal-Mart at 4-5AM, buy 15 boxes of TULA 7.62X39 for $5 each.
Sell at the local gun store for $8 a box.
The gun store sells it for $10 a box.
Make $45 for a short car trip.
From gun broker, it looks like 7.62X39 is selling for around 40 cents a round.
I could probably spare some at that price.
Our Walmart - and I understood it's a national rule - allows only three boxes per customer per day. You can play the "shop in the morning, shop in the evening" bit to catch a different attendant. That gets you six boxes a day, as long as the stock holds up (unlikely the evening visit will garner much).
In the stores I’ve seen boxes are limited to 3/customer/day. 22LR is limited to 1 box. Still doesn’t stop the frigging employees from snapping it up before anybody else though. I’ve seen this.