I think there is also a chicken-egg problem in almost every country that doesn't use English as official language:
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 --> to live there you need a job --> back to start
Different counties have different tolerances regarding how quick you pick up the local language. For Germany and France this tolerance is almost 0, for Netherlands it's much higher.
> 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).
In Germany, if you are an non-software Engineer, you MUST have an excellent level of the language. I have not seen a single Engineering position that doesn't require C1.
Anecdotally I've noticed that among the coworkers I've had from other countries, the ones who manage to learn danish and stay, have generally been in areas with lower density of foreign workers.
My theory is that in areas with lower densities of foreign nationals, you'd benefit more socially form learning the local language.