Screening tests and "case studies"/homework that takes 10-20 hours of time are abundant to weed out anyone who might be a pain to manage. They don't want independent thinkers or challengers who think out of the box, they just want 'doers' who will follow every twist and turn of senior management 'vision'.
As a non-German or non-EU, they then offer you a craptastic package of maybe 40-60k EUR before taxes (local Germans will get anywhere from 60-90k for a similar position). If you say no, congrats, they've succeeded in weeding out the next group of annoyances: anyone who wants to be compensated fairly.
The result is startups get the exact kind of workers they love - the kind that is easily exploited both in terms of work quantity and financially.
European startups like to whine about "shortage of talent" but what they're really complaining about is the lack of total naive locals and foreign talent willing to move to be exploited. Also startups in Europe usually DO NOT adhere to the "EU work life balance" that is parroted around the internet. You get worked like you're in America, minus the American salaries.