Most of those active have jobs of some kind. Their income from the trade is carefully controlled by those who run them. They only ever make reasonable profit. They spend what they get and are always in need of more money. As their involvement grows so do their costs.
Families are the best cover and make the best traders.
Contrary to common belief, single mothers are considered a liability because they attract outsiders and are more likely to be the focus of police attention as their children grow and start to get into trouble. The police have very limited powers to deal with the situation outlined above. The geography of the area is against them. Taxi-drivers gain benefits for keeping watch on police movements. Unless a major violent incident occurs through some over reaction during a punishment beating.