Texas-based RealPage and nine real-estate giants have been hit with a lawsuit that claims the software developer formed a "cartel" with the landlords to drive up rent in cities where housing is in high demand in the US.Set it too low and you may not cover the mortgage and other costs (if applicable) as well as miss out on profit.Following an investigation that sparked the above lawsuit, ProPublica reported the code ingests data including rent for surrounding homes to figure out an optimal price.Indeed, according to the lawsuit, RealPage boasted that its software drives "rental rate improvements, year over year, between 5 percent and 12 percent in every market."Renters suffer by having to pay more while landlords benefit by helping each other raise market prices, the plaintiffs alleged."