> If you are not an engineer you must have an almost excellent level of local language --> an excellent level of a language is only possible if you are immersed daily over a long time and have the time to study

I disagree: for many jobs, it is expected that you have a decent level of English, but at least in Germany, you are often not immersed a lot in English. So you have to get decent in English with barely any immersion.

I thus have a feeling that because many Germans had to learn hard to get somewhat decent in English on their own, they have the same expectation on immigrants to learn really hard on their own to get good in German fast (without demanding immersion).