Its easy to say the right things from the outside but when you enter the sausage factory you see how the sausage is made and realize how hard/impossible it is to really change things
CL offered them a mobile license and Padmapper is primarily a web only application.
Besides this trying to search for an apartment on mobile would be incredibly tedious. And this is likely why CL is willing to offer a mobile license.
But that is where the source of the problem is - CL has the largest user base for listing and classifieds on the internet and since they have the monopoly on this they have never felt the need to improve the experience on their site. Now that padmapper has started getting large number of users CL feels threatened and is suing them to shut them down.