Earlier quoted context omitted.
This is simply not true, throughout most of Europe your work permit is tied to your employment until you qualify for permanent residence permit (typically after 3 years).
Is this a recent thing? I'm in the UK under a Tier 1 (a points based, highly skilled migrants visa) and can work almost without restriction (I can't be a doctor or professional sports person). Even under the working holiday maker there were no restrictions to your employer.
I am in Norway and have a number of migrant friends throughout Scandinavia and mainland Europe. It's all very similar, with exception of Swiss (where permanent residence for a worker is nearly unobtainable).