$15/hour for unskilled labor? Have these people ever seen a 'Supply and Demand' graph?
Yep --- an over-abundance of cheap labor will keep their wages down -- even many illegals realize this -- and ironically not pro-open-borders like the employers of illegals are.
The problem also with the $15 an hour job that might be 4 hours a day, 2 or 3 days a week ---- the cost of living is so very high in San Francisco --- that kind of wage doesn't begin to cover the costs of the health care, education, housing costs etc of their large families.
In his low wage region an illegal can get somewhere between $15 to $30 an hour for loading bales of hay --- but that's pretty hard physical work and they can't do it 8 hours straight. You see these old guys out there in 100 plus temperatures --- after an hour they're collapsing.