They came from all over, looking for a place with manicured neighborhoods, nice cribs that would handsomely shelter them from the elements, jobs that would give them spending money far above just necessities, and uber-security from rank criminal elements. Their goal was to reach Fat City.
     By boat they came, by land, and by air. Catching sight of the Statue of Mr. Moneybags in the harbor they felt like they were almost there and then those in the halls of power closed the door. "Not In Our Backyard" said they.
"Where shall we go?" said the leader of the caravan, for they had by then assembled and elected a leader to represent them. 
      "Back to wherever you came from" said those representing Fat City.
"But...."
"No buts. Go"
     And so they went, back to where they came from. They blended back into the countries that they had tried to emigrate from, and things were all good and well for the people in Fat City, for they were safe. No gang thugs, anchor babies, stealing of jobs, contrarian political views, clamoring for unearned benefits, or being burdens on the existing system in any way.
        Life went on. 
        And then one day, not long afterward, the people in Fat City started noticing a decline in vitality. Necessary services weren't being provided in a timely manner. Even though those service jobs were heavily advertised almost nobody in Fat City wanted them. Of any actual candidates to fill those positions there were very few, and then to further the malaise, Fat City and other cities needing people to man their many and varied open positions got into bidding wars with each other, and the bidding was intense. Yet still the shortage of available labor was great. A.I. was supposed to have prevented this but A.I. could only fill so many slots, and it was expensive. What to do, what to do?

     Perhaps the door should be opened somewhat, said some, the door to immigration again, but those few brave ones risked censure for uttering such heresy. Their reputations could be attacked, now that they had spoken. 
     "No" said the ones in positions of opening the door. "We cannot. Our standard of living is threatened by any change in the social order (and balance of power) that we have established. We would rather struggle with the labor shortfall than allow residency. Our solution is we will offer temporary residency. For a time, they can live here, then they must leave"
         "Who wants that?" said the concerned. 
          "They that want to live here do. We will offer them jobs that don't pay very well, but.... ...compared to the wages in their home countries, they will feel like kings. We will rotate them in, then rotate them out. Don't worry- they'll be 'rich' when they get sent back, they’ll take their savings with them. While they're here they will live in zones that we will establish, contract labor zones, though they won’t be mentioned as such"
          "Sounds totally impractical and frightfully expensive. Are you talking labor camps? Who would ever want to live in a place like that?"
         "Our way or the highway"
         "I think they'd rather keep going on their caravan. They don't want temporary anything".

And that's the crux of it, isn't it? Whether it be neighborhoods as welcoming as labor camps, or tent cities, or homeless shelters, or 'outpatient mental health treatment', dealing with the problem of human affairs in a half-assed manner only keeps people on the road (or living next to it).
      As to the mobile ones, on the road they will be, heading for whichever country will take them in, until they can get to a place where they can actually have a decent sort of life. No place like Fat City or any other wants to deal with the problem, but people keep being born and the problem only gets bigger. The current immigrant caravan story that’s playing out now won't stay on the front page very long but it, and others like it, show no sign of going away.