Well, quite. But it seems that, for whatever reason, the migrant workers (or, you know, expats as we'd say if it were the English going abroad) tend to be lower

Well, quite. But it seems that, for whatever reason, the migrant workers (or, you know, expats as we'd say if it were the English going abroad) tend to be lower-skilled and, as you say, often their command of the local language is questionable. It's not a dig at people from Africa and Asia in any way, but the selection bias is obvious.