In Germany, the broker fee is a one time payment. That makes for an complicated calculation, as rentals are usually not fixed-term, and people will expect to stay for several years or decades. Is 900 EUR per month + 1,800 Euro one time payment better or worse than 1,000 Euro per month without a broker fee? Most people do not think like that. 900 < 1,000 Euro, end of story.

Of course, the real problem was that the landlords did not both to negotiate the brokers fee. There was a maximum broker fee defined by law, and everyone just charged the maximum. Not anymore!