How is it that Lewinsky and Tripp escaped the clinton style retribution?
They didn't, they just got their character assassinated.
After Linda Tripp learned that the Clintons had learned that the FBI had learned that the last person Vince Foster spoke to in the White House was Tripp, Tripp became very afraid and began taping her phone calls, including those from Lewinsky.
Those tapes established the needed evidence against Clinton and once Ken Starr got them there was no way to dilute the damage done. A living, ridiculed Tripp was either to deal with than a martyr. Although Clinton got off easy with the murder of James McDougal.
Linda Tripp saved her own life and that of Monica Lewinsky with those tapes.
The Clintons are amazing. Bill had his spouse's lover killed and his lover's spouse killed. And, Webb Hubbell is obviously the father of Chelsea, just look at photos and Bill has claimed to women that he is sterile.
They were too high profile. After Vince, it may have been too obvious.
Shooting someone in the head who has your genitals in her mouth is something to be avoided.