It exists is every market. What businessman is so stupid as to not know (or even want to know) what his competitors are charging for similar products?
At the same time, not every business caters to the retail bottom and margins get very high among many companies without so-called collusion.
Knowing what he charges is trivial. Knowing the other seller's constraints is what eveyone wants to know - how much longer will he survive selling at that price? how is he able to profit at that price? etc.
But the price is no secret. Just walk in the store and look at the price.
[What businessman is so stupid as to not know (or even want to know) what his competitors are charging for similar products?]
That isn't what is necessary. What would be necessary is knowing how his competitor would react to changing prices.