That's a great question/observation,Lilo....
and as others have said before, being a good earner gets you a pass most of the time. DeMeo and his crew, were chopping up luxury vehicles and selling them to the saudi's for a premium I'm sure. As well as being ass deep in the coke trade. Plus most other crews were afraid of them due to their mechanized killing methods, (see "murder machine")
Even Gotti was aprehensive about visiting them, as well as Nino Gaggi's nephew Dominic Montiglio. I personally think that the average Capo's ego, or whomever is ordering the hit, doesn't think that the'll be wiretapped, or if so the code they use for a hit, will be cracked. Bottom line, I think you kick back enough for the boss, you can kill a guy just to take over his rackets.....just my observation, I think the esteemed Turnbull could probably add to this.