The Mafia has gotten much more cautious about making guys because of the Law Enforcement infiltrations of the past.
Guys like Joe Pistone (Brasco) ,Jack Garcia (Falcone),and Ed Robb(Supposed owner of the King's Court in Fla) really made them overly paranoid.
According to Pistone,after his operation ended,the Mob re-instated the old rule about guys making their bones to become made men.
Also,the prospective member must be vouched for by two guys,not one.The sponsors must have known the candidate at least 15-20 years.
With the constant technology advances and better intelligence,the Feds are able to do quite a number on the Families from the outside. I agree with the other posters that the only real avenue for getting inside info is to jam a guy up on a major charge and try to flip him. Bear in mind that in the Rico era,it is much easier for a guy to be facing 50 to life for relatively minor stuff than it was years ago.