It is a ploy to keep wages low and unfortunately it seems to be working as most employees have bought into this belief that nobody will hire you anymore if you job hop every 2-3 years, at least in traditional German engineering companies, although it might be more lax in Berlin's hip software scene.

Germany is indeed a country of engineers, but poorly paid ones.

And yet Germany's engineer salaries are still substantially better than, say, France, let alone Spain or Italy.

In the large, European salaries for technical professionals are just way worse than American equivalents.