"Internationally, unregulated border crossimgs are a drain on the mother country. " I would agree that they are perceived to be those things. I think that the evidence, certainly so far as the UK and Ireland are concerned, is that they make a positive contribution.

As to your second paragraph, that is true (though some would call it racist). but, again, I would argue that such cultural changes are beneficial and ought not to be feared or seen as 'disrupting the comfort' of the host. There are laws to deal with anything that transgresses cultural norms beyond reasonal;e limits.