Go look up the Mietenspiegel price for your flat in your neighborhood, then pop open Immoscout and try and find one for that price.

Price controls = supply shortages. Basic principal of market economics.

But how does the market suffer from that? It implies that the Mietenspiegel is a bad policy. It only protects from price gauging or price dumping. If you are living in Berlin I would highly recommend looking up if you're paying too much.

Lines of 50 people to see an apartment sounds like a huge waste of man hours, which cost money to economy. This waste also grows quadratically: more people searching for longer.