Of course child molestation is exponentially more serious than pickpocketing but the principle's the same. Kill the kid and she/he can't tesitfy against you.
No, you wouldn't.
One of the most serious mistaken thought patterns among conservatives is the same mistake progressives make -- expecting perfection! or nothing.
There is no perfect solution and there never can be. That is why science exists, to try various things and test the results, under a variety of conditions. There will never be a fool-proof answer to this problem. But what we are doing now clearly isn't good enough.