Mafia exists because legal entities refuse to take responsibilities —- oh it’s too expensive to do X so we will leave it alone or legalize it. So eventually the underground takes over and Mafia becomes quasi governments.

To eradicate you need a stronger central government that is willing to send its probes into the deepest of the society and has a strong hand. Unfortunately this also has unforeseen consequences as well so is not everyone’s cup. Some societies prefer a stronger central government and some don’t.