Not actually true outside the major metropolitan area’s.
And too many of those “Jobs” are crap wage part-time “Service” jobs.
Some of us are not suited to paring toe-nails, massaging the obese, UBER driving, or flipping burgers.
In the rural area’s jobs that can support a decent life are still hard to find.
Too many are taken by illegals who depress wages across the area, others are really only suitable for the young and strong.
Add in the current trend of only taking applications on-line, a great way to block those over fifty or so without active age discrimination.
None of which makes Sanders any less of an idiot*.
*My apology for any offense to idiots this observation may cause.
This is practically a given, and has always been true, since the turn of the 20th century. People flocked to the big cities for jobs and good wages.