The average salary is 4900 Euro and after tax this will be 2900 Euro !!! Even software engineers in a poor country like Ukraine make more money after tax than that and they also have much lower expenses comparing to Germany.
So why someone living in Germany will spend a lot of time for study, learning all the technologies etc if you will only earn 15% more money than a cleaning guy without any education and who can spend all his free time with friends instead of improving qualification?
So Germany is a failed state for software developers.