This happens at Walmart Canada all the time. The policy there is to slash 10$ off shelf price (or free for anything 10 or less).
Since COVID, Walmart has stopped having immediate fixes of the problem.
Since 2020, I have accumulated about $1200 in free merchandise using the above. Almost always food.
The disastrous Target Canada (iirc) was similar; obviously nobody cared at all.
Publix in the southeast US will give you anything that rings up wrong for free. I shopped there for 20+ years and only remember getting a handful of things free.
I'm in Toronto and I've never had anything ring up incorrectly at Wal-Mart. I can't recall ever having anything ring up incorrectly anywhere else, either. There have maybe been a couple of times where a sale price didn't apply to all the SKUs I thought it did.