But that’s the thing, it’s not “collusion” in the sense that rental companies all conspired to raise rates at the same time. None of them actually collaborated with each other.
At the same time, the software isn’t designed for collusion at all. It is just hoovering up public data. It is not doing anything that the companies couldn’t do themselves, and they have to keep all their client data separate.
The end result is collusion, once enough companies are using this software that their price increases drive the public market and then get sucked into the algorithm and generate more price increases. But there is no action by any party which a court can point to and shout “Collusion!”. There are enough independent actions that just happen to go in the same direction. That’s the reason why new legislation may be necessary, in order to catch this sort of distributed algorithmically-enabled collusion.