Of course they do know, that's why Denmark passed new law reducing the welfare support from ridiculous 11.000 DKK to less ridiculous 6000 DKK last year, which is still good bait for economical migrants nonetheless. The same goes for Germany, where new conception of immigration laws have been proposed and accepted recently, reducing welfare benefits and tightening obligations for migrants. Perhaps someone started realizing that the system is flawed and broken, what do you think?
http://www.spiegel.de/politik/ausland/daenemark-weniger-geld-fuer-asylbewerber-a-1049949.html
edit: This is not populism, you dork.