The Camorra doesn't have to emigrate like the Calabrians do nor do they need to. It's all about geography and culture.
Naples as a city is rather big and it's surrounding areas are densely populated therefore the napolitani have a huge retail market to work with.
Calabria is the opposite mainly composed of smaller towns in the country side. The strongest most powerful families come from villages with no more than 5000 people. Calabrias largest city has maybe 300000k people. Compare that to Naples or even Palermo.
The calabrians emigrated and exported their crime syndicate with it. They have blood relatives in Canada Australia Germany Argentina and USA. The reason you hear less of them is that culturally speaking they are less flamboyant than either Sicilians and napolitani. They fly under the radar and would rather not be known....which by product makes their syndicate less interesting for tabloids as opposed to some camorra war or don Corleone war here in Montreal.
The truth is that everyone in italy now fears and respects the ndrangheta...when they talk others follow. Here's a video of how Cosa nostra in its hey day paid off ndrangheta just to avoid them.