Heres a good article about how the mafia has changed over the years.
http://www.bunker8.pwp.blueyonder.co.uk/orgcrim/3802.htm

from mafia to gangster?

We can now turn to the second question. The rapid expansion of the Mob based on the economic criminality of the Prohibition era and subsequent decades raises the question of how far Italian-American organised crime moved away from the Sicilian model in which the organisation continues to seek not only wealth but political control, legitimacy and a role in settling disputes in the community from which it emerges, and becomes, simply a form of illegal wealth accumulation-- crime as a form of "forced entry" into the ranks of the wealthy.

The German sociologist Henner Hess (1998) Mafia and Mafiosi: Origin, Power and Myth argues that the American Mafia began to move away from this community mediation role. This would be expected as the Italian-American community achieved upward social mobility and moved out of the ghetto and as the mafia widened its economic activities outside the local community. The mafiosi thus loses status and legitimacy and becomes a criminal pure and simple:

“because he has no necessary protective or mediatory function to fulfil within the social system he also possesses no legitimacy in popular morality; that is, he is no longer a mafioso but a criminal... He grants no audiences and nobody calls on him. He is... to the general public an anonymous big-city criminal, with no resemblance to the universally known and respected mafioso of the Sicilian village.” (Hess 1998: 172-3)

The bureaucratic-corporate model portrayed by Cressey would be quite consistent with a criminal organisation that lost its community roots and functions and became simply a money-making machine. But then so would the more decentralised family-oriented structure portrayed by the Iannis. There are plenty of small 'family firms' in modern organised crime. But they tend to concentrate on money-making rather than gaining status and respect through sorting out conflicts in the communities within which they operate.

But if we return to the opening scene from the first Godfather movie, even if it is rather a caricature of the Mafia, we see, even in the period after the Second World War, the American Mafia as still very much rooted in the Italian-American immigrant community. Here the activities of mediation, settling disputes, helping individuals, giving 'justice' to Mr Bonasera, are still very much alive, though not quite in their old Sicilian form. That is to say it is less a question of the weakness or absence of the legitimate state and law enforcement agencies than it is a desire to keep things out of sight of the law enforcement agencies and within 'our' community and impose 'our' values and standards of justice. Don Vito Corleone (Marlon Brando) says to Mr Bonasera "But why didn't you come to me in the first place? Why did you go to the police?" Mr Bonasera, it will be recalled, only came to the Don 'for justice' because he didn't get what he regarded as justice from the state. It was not a question of the weakness of the state.

As we shall see in more detail later the traditional Mafia in both its Sicilian and American versions, by retaining its orientation to prestige and status (through the respect that comes from fear) in its own communities, found itself at a disadvantage in relation to other more modern organised crime groups when it came to taking advantage of illegal money-making opportunities. This is broadly the argument of the Italian sociologist Letizia Paoli in her book: Mafia Brotherhoods: Organized Crime, Italian Style . (Oxford University Press, 2003) She argues that the Mafia, both in Italy and the US, clings to its traditional focus on the retention of a local political power base. She argues that this has been to a considerable extent at the expense of opportunities to engage in a more modern purely entrepreneural criminality. The latter would require in the present period a more flexible shifting form of organisation and the ability to operate globally rather than be tied too closely to local communities and family networks. She argues that this was the basic cause of the decline of the old Mob during the 1980s.