Quote ="Riderofthepalehorse"Thomas Minns , Zak Hardaker, Ben Barba, Ben Johnson, Lance Armstrong, and a list of super athletes, in various sports, only one rule, drugs=out. No compromise rid sport of this cancer, no club politics, do drugs your finished. FOR ALL
Examples set problem gone.'"
Ben Johnson was allowed back after failing a drugs test for PEDs. It was only after he failed a second test that he was banned for life.
Lance Armstrong was well known as a cheat during his entire cycling career, especially during his TdF victories. There's no evidence for this, but it is understood that UCI looked the other way, due to his prestige bringing in fans.
The three rugby players you mentioned all tested positive for recreational drugs and not PEDs. You cannot compare these, since they are complete separate entities.
The IAAF did used to issue lifetime bans, but these were rescinded when they went to the Court of European rights, who overturned them.
Lifetime bans do not work. You are essentially calling for a life sentence for one indiscretion, which is far too harsh. Where humans are, bad decisions will be made.