Did you get a competitive salary or ~1% of share of the company as an early employee? If not, you were used. The aforementioned is a typical Berlin startup. A favorite of mine is when a company tries to pay you with debt, i.e. instead of being just a developer, you become a banker for your future boss' idea. I wish I were joking...
Not hard at all, there is plenty of information about wages in IT. If you understand the root of the article, the US versus Europe comparison, take Silicon Valley numbers and compare to €58k and you will find it ridiculously low. Damn, you get more in Romania (Bucharest or Cluj), I am not kidding you.
What I see in Germany is that some of the startups are basically contracted by larger companies, tasked to develop complex solutions for a fraction of the price that an established company would require for the same task.
I wouldn't really consider those startups since they're not trying to develop their own product for a market segment. Those are more like small development shops (there are a lot of those here in the US as well).
Having worked with a multitude of startups over the years I can say that none of them have behaved in this way in the Nordics.