As I said, the intent is the key. If I intend to murder you, but my plot is foiled by external forces, or I am subdued in the attempt, that is absolutely punishable to the same extent as an actual murder.
And you'll find that sentences don't make too much differentiation between murder and attempted murder.
If I try to blow up a plane but my bomb fails to go off - if I tried to blow up the plane and that was my intent - then I am guilty of pre-meditated murder, just one that I failed to execute.
In the eyes of most people, they are every bit as bad. And the punishments handed down reflect this.
To argue that a failed murder attempt is not as serious as a real murder is madness. We're not talking about a guy who had 2nd thoughts and decided against it. We're talking about a guy who tried to kill someone and failed.