About the same could be said of just about any case of collusion/price-fixing/other anti-competitive behaviour. "[Airline X] would never do anything to help or benefit [Airlines Y or Z], which are its most important competitors in the [region] air cargo market" . "[DRAM Chipmaker A] would never do anything to help or benefit [DRAM Chipmaker B], the latter is [DRAM Chipmaker A]'s largest and most important competitor". "Those bakeries would ever do anything to help each other, because they're each other's biggest and most important domestic competitors". And yet all have happened.

As a market grows more and more concentrated, the task of dividing the market requires the involvement of fewer and fewer people. It's very difficult to communicate effectively while keeping illegal practices hidden if you have, say, a couple dozen airlines around the world rigging air cargo prices. But the more oligopolistic a market gets, the simpler anti-competitive behaviour becomes. Businesses may stay out of each other's territories without ever overtly colluding to do so, simply because it's clearly rational for both to do so.

The challenge for air travel in Canada is that it is massively concentrated, with AC and WS forming, for a number of years, close to a duopoly. The presence of firms like TS and WG kept some competition at the margins, and while AC and WS each had their geographic focuses, any attempt by one to significantly increase prices in one area would likely lead the other to deploy some capacity in the same area to earn some of the excess profits, keeping prices somewhat in check but allowing for reasonable profitability. But now we have a shortage of two of the key inputs to commercial flying, pilots and aircraft. There isn't really excess capacity among the two big players, so the profit-maximizing move is to focus on the core, which allows for more efficient deployment of your scarce resources and minimization of your own costs. So, even if WS and AC haven't colluded, their individual incentives may be driving them to make decisions that are anti-competitive and poor for Canadian consumers.