I think it's often monopolies enforced by violence and corruption.
Gang tattoos to limit the mobility of their labor, duopolies to minimize conflict but maintain most of the benefits of a monopoly, squeezing upstream suppliers by playing them off each other, geographically-differentiated pricing and much more.
The violence is obviously the biggest difference, but even the rest serves as a warning not to drop regulation entirely.
You don’t need a government necessarily to enforce those rights, but free exchange of goods and labor cannot exist if violence is possible to coerce those exchanges.