You hear a lot more about Bugsy Siegel and Mickey Coen than you do about Jack Dragna or any other of the LA family members. I think New York always ran things in Hollywood low key through their Jewish connections, for whatever reason. The only LA Family member really big in this scene was Johnny Roselli, who I believe was actually Chicago Outfit, and who was sent to work with the LA family. It's hard to say why the LA family never really prospered in the commission's heyday, although I recall they were powerful during Prohibition. My guess is that by the time the Commission was gaining power, the LAPD was recruiting a lot of southern white racists that viewed Italians as an ethnic minority.