Actually, wages aren't that low. Taxes are high, specifically the tax brackets mess things a bit! Net salary is a bit over 55% of your gross income when you account for health insurance, pension, taxes AND you don't pay church tax.
Examples:
4000Euro/Month gross, net == ~2395 Euro
5000Euro/Month gross, net == ~2897 Euro
It would be interesting to see how much employees in Berlin cost their employers too.