The advertising campaign that Rushdie describes is still going on in many subtle ways. In the United Kingdom, and even more so in the United States, the 'land of opportunity' perception is readily endorsed. It is, in fact, a vital component of both nation's self-images. Thus, the irony seen in these country's immigration policies becomes obvious.
Immigrants are only immigrants on their side of the border.
As soon as they cross the line, they become invaders. If they try to work, they are accused of stealing jobs. If they do not work, they become parasites of the state. In either case, their presence is, at best, an economic disaster. However, some would argue that the economic arguments are an erroneous basis employed to cloak a more basic motive.