In the past there was always demand for "unskilled" (manual) labor where displaced workers could land to without long (re)training, and possibly even gain skills on the job. But that job marked has dramatically diminished especially in the west; there are only so many burgers to be flipped. Somewhat famously during industrial revolution displaced agricultural workers (e.g. farmhands) ended up mass-migrating to cities doing factory work under extremely exploitative conditions. And that never truly got resolved, we just brushed the issue under the rug by pushing manual labor to third world countries where the problems could remain out of sight.