Hm. I think the mafia thing is mostly an excuse. When people- also in Italy- think of the mafia, they think of a vast and powerful criminal organisation- something like an evil multinational- with the power to infiltrate the State and resist to its attacks. The good people of southern Italy then love to depict themselves as the victims of this malignant entity and of the inability of the State to eradicate it.

However I doubt the situation is so simple. First, while the mafia might have some form of primitive organisation, it's probably more akin to a coordination of warlords than a company board. Second, it doesn't exist in as vacuum: in the south of Italy illegal behaviour is widespread: corruption, welfare system frauds, absenteeism of civil servants and public employees, absurd privileges of politicians. Politicians often display a peculiar rhetoric, as sonorous as it is utterly void of any concrete meaning. The predominant culture is drenched in self victimisation and apathy.

So I'd take the "it's the mafia" refrain with a grain of salt.

Well, the impression was less one of "a large organized crime syndicate" and more "wide-spread, pervasive, moderately organized corruption". So, what you described.

The mafia might now be born in today's environment, but it was born, and still exists, even if its power is receding, and it's been strong enough for many decades to hamper the state's infrastructure.

The roads that weren't built or that were poorly built still are poor roads, etc, even if the situation has improved.