[0] https://worldpopulationreview.com/country-rankings/percentag...
Welcoming people in because "no-one wants to do those jobs" is very much a luxury belief of the well off.
What I think has happened culturally is that Americans see us as the shining beacon on the hill, where everyone wants to be, and so we feel sympathetic to those who will do whatever it takes to come here. There are lots of cultural references historically that reinforce this mythology. Call it American Exceptionalism or whatever, but the mythology is real.
Between our own loss in confidence and the onslaught of 'America Bad' inundating the online dialogue, this mythology is dying in a hurry. Makes me a little sad, honestly, because I am of the opinion that a nation benefits from a strong mythology. Sometimes that is served by religion, but in the US it has for a long time been 'Land of Opportunity' and associated beliefs. I dare anyone to go to the US Capitol tour and watch that 15 minute intro video about the founding of the country and not come away with a tear in their eye. It's quite moving, even if it is largely a fabrication.