Imagine you ran a soup kitchen or if you were a “customer” of a charity-run soup kitchen. In both cases among your concerns would be how much soup you had to go around. Additional customers of the soup kitchen in a sense are bad for you. Supply is very much fixed in the short run; therefore, additional people on the receiving line just means less soup for everyone else.
More technically, supply is (likely) fairly inelastic—or at least is likely to be perceived to be. A big increase in demand would not result a very big increase in soup supplied. Since price cannot rise, the predicament would be a very ugly shortage.
Keep this analogy in mind . . .
An underappreciated incumbent constituency naturally opposed to both legal and illegal immigration are those associated with public government schools. These constituencies naturally will see immigrants and more specifically the children of immigrants as nothing more than additional minds to feed education out of the limited kitchen of the education system.
From the standpoint of the government school system (unions, teachers, administrators, and taxpayers) additional immigrants appear to the naïve eye as a surge in demand with no ability to increase supply (movement along the supply curve to be technical yet again). To a great many of those who are sending their kids to government schools, these are just more people taking away “free” education which implies less opportunity for their own kids.
I have witnessed such reasoning working with people who are very much involved with their local, rural school boards. These well-meaning folks are very protective of their schools and like them as they are ‘thank you very much’. They worry about voucher systems because that is a disruptor threatening their applecart—’things are fine; how can this help US?’. Similarly, they worry about immigrants because ‘where would they go?’
At the risk of unfair labeling, many of these opponents suffer from a small-town nearsightedness that limits their ability to think about large changes.
I have also witnessed such reasoning working with people who are very much involved with their local, urban schools. These well-meaning folks are very concerned with how thin a poorly used budget (notice I did not say small) can be stretched. They worry about voucher systems for the same reasons above but unfortunately with a greater emphasis on how vouchers would hurt them as incumbents than on an effect on (failing) schools, which they will not spend much effort defending. Similarly, they worry about immigrants because ‘how could we possibly accommodate them?’
So before objections based on cultural-influence concerns and all the other prejudices, in the interaction of education and immigration we first start with people’s poor grasp of economics and the tribalistic threat they feel that somebody is going to come in and take something that they’ve been paying for.
P.S. Someday we will understand the lessons of Julian Simon and see immigrants as people who come with two hands, not just one mouth—brains not stomachs.