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various EU countries have a law that states that all jobs have to be advertised domestically for a period of time before they are opened up to international applicants
The UK has this (or at least used to have it) for non-UK/EU applicants. I remember having to do these interviews at a previous employer and it was a total farce. You'd have a candidate in mind, then "tick the box" for a couple of UK/EU candidates.
In other words the same reason why various EU countries have a law that states that all jobs have to be advertised domestically for a period of time before they are opened up to international applicants.