The truth is that rents in Berlin are exceptionally cheap compared to other major cities. Try finding a flat in London or Paris for <10€/square meter/month that is half an hour bike ride away from the city center.
The only way to keep rents this low in the face of rising demand is public housing that is rented out below market rates to low income tenants, or via a lottery.
The only way to keep rents this low in the face of rising demand is public housing that is rented out below market rates to low income tenants, or via a lottery.