No it isn't. It's only easy to get rid of the few that get caught. There's no way to know how many are out there. Also, children who get abused have a higher probability of becoming abusers themselves. What are you going to do? Shoot them too?
Yes it is, 1 at a time, and from the recent arrests made by multiple police forces on different continents they are being caught by the hundreds. I've never heard of a dead pedophile ever re-offending.
It is quite easy for those who have been fortunate enough to not have had to deal with something like this to plead for "treatment" or "therapy". Try having to piece together, ever so slowly, the mental and emotional feelings (without mentioning the physical scars) of a 9, 10, 12 year old child (with little chance of complete success) only to watch the predator walk out of jail 4 years later. Deal with that and then come talk to me about treatment when you know full well they WILL do it again.
There is a greater chance a child of sexual abuse becoming depressed and committing suicide than it is for them to become an abuser themselves.
As far as I'm concerned the father in the OP's original thread should have finished the job considering how understanding the police officers in his area were. Even if they were to press charges against him I find it hard to believe a jury of 12 reasonable people would convict him. Now THAT would be true justice in my eyes.