I've experienced the annoying thing a few times recently. I wanted to buy a product, looked for the price and there was nothing written on it. The price tag on the rack was missing for the exact product I was interested in.
If the price had been on the product, this wouldn't have been a problem!

Or there were two products in a rack of a similar product. Which product does the price on the rack refer to? This is where it gets complicated and unclear. If the price had been on the product, then....

At the checkout, the cashier types in the price and I get the impression that my product should be cheaper, a special offer. Because there is no price on the product, I can't prove my impression (of course I could be wrong). But at this moment I am at the mercy of the cashier's information, even if the computer makes a mistake.
If there was a price on the product, it would be clear at the till. But because this is not the case, it's a case of statement against statement. I find that annoying!

Fortunately, I then went to the information desk, where the matter was resolved in my favor. But if the price had been on the product, then...