One of my favorite purged remarks seems applicable here:
* There is a certain group of people who don't like governmental interference, and it gives them great pleasure to hire unlicensed people
Whatever the attraction to undocumented labor, unlicensed handymen, exploited internships, expendable apprenticeships / temps, and perhaps family members, little can rival the primal exchange surrendered by indentured servitude.
The exception with civilized Owner/Builders in Germany, may come from that country's strict record keeping for taxes, severe fines for meter tampering (changes in demand), and public notices for the prosecuted, village idiots.
Without similar regulation, contractors in the lawless Owner/Builder world must try harder to adapt to the wild, or try harder to prevaricate.