Berlin startups are infamous for hiring foreigners from countries with low salaries, ideally from outside of EU (so no free movement of workers with Germany) and paying them below the market salary. Low pay + dealing with German bureaucracy + sky rocketing prices of everything in Berlin = person has a problem.
As for Axel Springer - their understanding of internet innovation is quite... "skewed". e.g. as some kind of manifest they blocked their tabloid's website (bild.de) for web browsers with enabled ad blockers or they are notorious for suing developers of ad blockers:
Chinese developer working in a Berlin startup here. I agree the Berlin startups do hire a lot of foreingers (there is a report stating that 49% of employees are foreigners), and it drives the salary down, but I can say my salary is the same level as others developers, as developers has such a huge demand here that you can change jobs freely, unlike American H1B visa.
Also because the EU bluecard has a salary requirement, so they usually pays you the lower limit at least in order to get you here. That's the situation of my Mexican friend, he changed job as soon as he worked in the company for a year and get better paid.
Second this (as another non-EU citizen working in Berlin) -- you have to make at least 38k euros per year to work in Germany as a foreigner, which is enough to live comfortably in Berlin IMO. However, as you said, there are definitely plenty of companies that are paying more than this. Changing jobs is a non-issue when you're on the ground.
This is too much exaggeration. If you can find another job, dealing with bureaucracy is piece of cake. You just go to Foreign Registration Office and change company name.