Comment by weitendorf

Is this not almost exactly what you get on apartments.com or zillow.com by just looking at the listed prices in an area?

I think you might have the problem backwards. Realpage was about buyer collusion, and that wouldn't look any different from the prices naturally just rising in a market with more demand/less supply because even sellers who aren't colluding would still raise their prices if they saw that that was the going rate in the area.

When there are multiple competing factors all influencing price simultaneously it's very hard to accurately determine how much any particular factor contributed, or what the "actual price" would have been without them.

This is actually essentially the problem that justifies markets as an efficient way to arrive at fair prices - it's computationally too expensive to calculate the precise supply/demand ratios at any given moment, and demand can change much faster than supply can adjust (and nobody could ever really know how elastic demand is for things like local housing markets anyway).

So sellers want to respond to changes in demand by raising prices, because the business model of housing rentals is matching short term demand/pricing/risk to long term costs/costs/risk. But every buyer has their own demand preferences and every supplier has a different product with different fixed costs, and everybody knows their own demand preference and ability to provide supply, so the aggregate price a market settles at "collapses" all that information without explicit coordination: https://en.wikipedia.org/wiki/Economic_calculation_problem

If there truly is an increase in demand, as a buyer you probably do want rents to increase, because otherwise you get shortages like in Berlin where there is nothing to rent. So that's why coordinating to withold inventory with other sellers is bad, it creates a shortage anyway and only a small number of participants need to do it to move the entire market