Why "natural, fair chance"? Of course they see what their competitors charge. That's one of the ingredients of a free market. The quicker they react, the quicker the information is dissipated in the free market.
It's trivial for every large retail store to just send someone to look at their competitor's prices and price at the same mark.
This is not feasible to do for B2B only products, such as bulk LCD panels, so it's a lot easier to prove pre-arranged price-fixing.