I think you are confusing "tech companies" with "web start-ups". Germany has a different focus than Silicon Valley and thus a different type of "tech" jobs as well. There are a lot of challenging engineering and IT jobs where you will work together with top-notch colleagues in industrial automation, mechanical engineering, etc.

Note that Elon Musk is still dreaming about building tunnel boring machinery, while at Herrenknecht you can already innovate in this field today.