I suspect this law does not apply in cases of fraud. If not, simple tag-switching would be rampant.

I recently learned that in some cases fines of mispriced goods were very low, leading to companies repeatedly failing tests - and over/undercharging their customers.

https://www.theguardian.com/us-news/2025/dec/03/customers-pa...

That seems shocking to me, but I guess I live in a country where the prices on the shelves are "final" (with no need to add taxes) and I think it would be immediately obvious if I'd been charged the wrong price for goods.