From what I know of the situation, a Turk can get a low level job in Germany... and that’s still a decent job, for a Turk, compared to “back home”. For a Greek, it’s not quite so good. But that may change...
I have not been to Germany, but a cousin and my Dad have, for extended times. My cousin (who’s pretty lib) was in particular stunned by how “2nd class” the Turks’ status is in Germany.
A Greek can probably do better not working in Greece than he can working in Germany.
And a second class gastarbeiter is probably better off than they would be in their village in Turkey. Germany does, however, have a huge Muslim problem as a result.