Earlier quoted context omitted.
.. why on earth would we preserve that? Should supermarkets not show prices?
Supermarkets should not have to disclose their COST prices, because these are non public negotiations, not a public offer to buy/sell. That so many people wilfully choose not to understand this distinction frustrates useful conversation.
Should that be legal? Maybe, maybe not. But there are plenty of laws out there that mandate that companies make pricing more transparent, because that is good for the end consumer.