That’s why it’s so brilliant. If you can develop an in-band system to coordinate arbitrary price increases between firms then you have plausible deniability. Who needs price fixing if you can just temporarily increase price, see who’s price matching algorithms follows, and act accordingly using an algorithm that acts so fast that consumers are none the wiser when the “negotiation” to increase price fails.

The fact that the impetus for the price increase is nothing more than to test if other firms will raise their prices to match an increase and has nothing to do with supply or demand of the product makes it transparent that this strategy achieves the effect of price fixing without the smoking gun of explicit negotiation and plausible deniability that they are simply engaging in “price leadership”.