How about this, instead of putting dogs down when they accidentally hurt a child, why not put sex offenders who hurt child down.

Probably because incarceration is an objectively superior method of dealing with them in almost every way. If we get the wrong person & imprison them, we can just let them out once evidence exonerates 'em. If we get the wrong person & kill them, then all we can offer is our apologies. The dragged out criminal proceedings required for the death penalty are also pretty rough on victims...

It seems that during incarceration the inmates have a way of dealing with them. For some reason the guards are never around.

Take them out back like old yeller

Agreed