Any individual can go out there and build a model for the rent price, the issue comes in when that model is able to coordinate everyone to keep the prices high and discourage competition/undercutting.
Showing that the average rent is this, the min and max are that, and the percentiles look like this is probably legal. Showing historical trends is also legal. Recommending a certain rent based on a single shared algorithm used by all the players begins to cross that line.
Colluding with other sellers to fix prices is illegal. That is the issue here.
Is it based on intent (you literally are training your model to be cooperative), or is it based on effect (your company is having this effect regardless of their intent -- e.g. Zillow might also be offending). Both of these will be hard to show in practice.
At least where I live, there are landlords who operate reasonably (reasonable rents, with safe and maintained properties, that respond quickly to issues), but there's so much demand relative to supply that it doesn't really affect the ones who are just trying to extract maximum profit.
Should have been obvious...
As long as there are financial speculators, price bubbles will happen. A massive recession can clear out speculators and burst price bubbles, whom will have in the meantime, fleeced the public for billions, as will as made many be homeless.
In commodities markets, the CFTC has different rules about what speculators can do vs real market participants (real producers and consumers). There are very few rules/laws that disincentivize real estate speculation and many forces that incentivize it. These algorithms are additional tools that help speculators maximize profit.
Housing has very limited supply and very inelastic demand. Prices will not come down unless there is another 2008 style recession. Speculators will continue to pile in and fleece renters maximally.
You might say well that’s just business, but the algorithmic price collusion is really not my biggest issue. I think there’s a different moral question we should ask. What is the number of single family properties a single company should own in a given market. Should they be allowed to own 100%? My silly libertarian friend would say why not? The market will correct. A stronger thinker would probably see that a legal limit probably makes sense.
If you want to know where bubbles came from, you should have just asked, its called monetary policy and is set by the federal reserve; sure, there was the great tulip mania of - no one gives a fuck it was a short lived commodity bubble that would look miniscule accounting for any amount of inflation you are willing to admit; today, the "bubble" is called debt, the purchasing power of your dollar must decrease, because the very existence of dollars necessarily implies there is a corresponding debt with interest, it turns out to that a pretty significant amount of the money being printed is being injected intravenously into the housing sector unlike the median wage, and you guys are always mystified that housing costs so much money, incentives matter.
If you want to regard this in a moral context, name your world religion and I will agree this second to obey their economic practices. There are many immoral philosphical ideas regarding economics that many regard as moral; religion is no exception, but I find that conceptually grounded in principles that have worked for thousands of years to keep people ethically bound despite ethnic differences and geographical seperation. There is far less to fear from islamic lending practices than whatever people "feel is right" in the heat of the moment.