[hueyluey]

>integration has huge costs

The point is whether is has more immediate benefits than costs. My sense is that it usually does (immigrant population contributes more economically that what they cost in taxes), at least in the countries I've checked. The exception might be countries that accept a huge amount of refugees (I dunno, just speculating)

If you have evidence to the contrary, please provide it.

[tored]

It depends entirely on what kind of immigration you are talking about, there are empirical evidence that certain type of immigration can be beneficial, but it also exist empirical evidence of the contrary, thus making a general claim is not possible without looking at the specifics, i.e. which immigrant group to what country and in what time.