It's not understanding the local rental market that's the problem. It's controlling enough of it that you can influence prices globally upwards outside of economic competition.

If 60% of a city's major property companies sign on with RealPage and *also* agree that they will not undercut the prices RealPage chooses (eliminating economic competition between the property companies), that's not just being a high information party, it's collusion.

The problem is that housing in major cities has a relatively fixed supply, so the colluding landlords know that even if a competitor undercuts them eventually they will simply fill their units and cease to be competition for new renters.