When I go to exchange money in kontors in Krakow, I go from Kontor to kontor and they have big flashing red lights telling you the prices.
I don't honestly see the problem here, they sold, he bought.
As you said yourself, it is basic economics.
How did he "just arrived, tour bus waiting" and him on Ulica Florianska (the main pedestrianised shopping street in centre of Krakow)???
If you are talking away to a friend and not paying attention
...when changing money, you've got stupid written all over you.
But the problem doesn't seem to be that they changed their rates, just that afterwards the tourist found a better rate.
The "We buy" info is displayed
The reporter, pretending to be a tourist
Would the sign change if he was dressed as a tourist, hare krishna or monk?
I don't think so.
I think this is just a fella who was too lazy to look after his money and people made money on it.
ONLY when he found out he could have gotten a better rate later he was annoyed.
"I bought perogi for 30zl but I am angry now because I found another place that sells them for 14zl..."