On the at-will thing, in addition to it being easier if the company has demonstrable financial problems as someone else mentioned, one thing that makes it less

On the at-will thing, in addition to it being easier if the company has demonstrable financial problems as someone else mentioned, one thing that makes it less of an issue is that usually when you start at a company in Germany you're given a fixed-term contract. It's only after your third contract (i.e. usually after two years) that you're required to get a permanent contract. In most cases if there's a real clash it's going to be sussed out in the first two years of employment, and during the first six months employees can be fired with no notice. The working hours thing, for better or worse, is broadly ignored in software companies. That said, hours aren't as extreme as in many American companies. For the parental leave, that only applies for companies with more than 15 employees, so the startups that it would affect are going to be more established. And while taking a year off is common, it's very rare for more to be taken with intent to return to the job.