You're effectively asking where do they find people keen to be enforcement goons against mostly-foreigners, with minimal oversight and no need for identification. There's a large number of guys ready to join this one - they're in local fascist groups in all the cities.

By lowering their standards a lot.

there are huge segments of the US economy that have not recovered and inflation is crushing people. housing is out of control.

no shortage of desperate bodies who'd happily take a GS wage with a pension

perhaps recruitment among the Proud Boys and similar groups