This phrase has been used ad nauseam in Europe and the US for at least 50 years by countless authors. It is supposed to give the reader a good feeling about an essentially abnormal and harmful situation.
Would any European/American object against picking grapes, cleaning offices, cleaning ships, mowing lawns, etc. at a rate of $100/hour? Of course not. Migrant workers destroy the labor market because they are always willing to work for less, thereby screwing the lowest segment of the native population.
Does it make economic sense that the migrant workers do this work? Their employers have certainly an advantage. But the society as a whole pays the price. Migrant workers may pay their fair share of taxes (as always reminded by left wing apologists), but these taxes do not pay for their usage of social services - especially since they tend to have more children than the local population. The low quality of education in California is a sad consequence: Proposition 13 was passed to prevent charging the local native population for the rising education costs and the state subsequently minimized the education layouts.
The long term costs of migrants - especially in Western Europe - make the economic rational even more questionable. The second generation does poorly in school and their parents are not able to control their children, which leads to a worrysome level of criminal behavior.
Finally, the acceptance of migrant workers decreases for their originating countries the pressure to be responsible for their citizens and indirectly towards the world community. Having no population policy in place and simply exporting continuously an excess of people that cannot find a decent living is a major source for the world's overpopulation that has created massive havoc on the globe in the previous century.
Your author should think twice before ever again paroting the canard "they do the work that we don't want to do". Edward Abbey coined the famous phrase "migrants give Republicans their cheap labor and Democrats their cheap cause". He summarized best the sickness of migrant labor.