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 --> 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.