That proving some things in court is easier than other things and by reducing down nuanced legal systems to "rich bad" doesn't help the situation any.
It was hard to pin down the mob boss to particular murder. They could get the lower level hitmen, sure, but tying it to the main boss was difficult. Recordings were not really a thing back then. Those that did talk were killed.
Rudy Giuliani (yes that Rudy Giuliani) had the first successful prosecution under RICO in the 1980's.
And just throwing the word “nuance” into a comment doesn’t a counter-argument make.