It's hidden in plain sight.
Signs of L.A.'s flourishing underground economy re everywhere, from the front of the Tommies burger stand on the corner of Pico and Sawtelle boulevards, where day laborers line up each morning, to kids' birthday parties in Beverly Hills, where undocumented nannies mind the children of the very rich.
There is also the drug trafficking on downtown's skid row, or the bartender who doesn't report all his tip income to the IRS, of the painter who will ...