They do not for a good and important reason.
We see today's immigrant invasions that came following the more subtle and useful to some invasion by a lesser threatening species.
With that blind eyed turn of the corrupt ones to the lesser invader came also to future destructive, lethal and toxic ones.
Gotta get them in there one way or another, so play like you are a sleep at the wheel, was the very way these set for that very exploitation, one to turn into the downfall of the nation they carried it out in.
When one greedy and corrupt idiot served their selves off the illegal immigrant trough in time the one who is malicious takes over what they established and it becomes their weapon against that nation the prior fool was in and over.
There has been a hijacking of what long ago was allowed to remain.
These new hijacking ones are full fledged enemies unto that nation it is being carried out on and have merged with even worse the enemy within who watched the successful damage the fool effects caused and it was like a drop of blood to the tongue of a hog for that one.
Bad brew, bad breed.