The majority of the gang members don't fight for power against Sonny, because they know very well what will happen to them if they do. Their weapons and their fancy suits are two major symbols of power, though just being one of Sonny's friends gives you alot of "respect" around town. Collogero enjoys being treated nice, even though it's mostly out of fear- he gets money, protection etc. The gang is very protective of their turf, they're like animals almost, they have to check out this stranger, check to see if the guy doesn't mean any harm,eye him, and then just stand back and observe..and if that one guy decides to get reckless, he's going to get disciplined and kicked out of town. The groups have a huge role in what happens in the town,
and seem to actually be running it.