Because if God doesn’t control human destiny, having given man free will, then why pray for miracles, for strength, for assistance?!
God can do miracles if it is within His desire, but when we pray, we should end all prayer with, "Thy will be done. not my will". We do pray for strength so we can be strong in the face of such disasters, and if by His will we are blessed to miss death by a mere second or sliver of space, then we are expected to understand that our time is not up yet.
However, we also pray to be in communion with God, and to learn what it is He wants us to do. We all have a calling, but how would you know if you do not ask Him what it is. God can and does grant miracles, but only it works for the better of His glory.
Ultimately you must understand that we are nothing without Him, and it is but by His grace we even live. Who are you to ask why God does what He does? Who are we to demand anything from Him. If you truly want an answer than ask Him. However, If you are to arrogant and proud to humble yourself before the One who created everything that is, then I pity you.
As for me, I thank God that I wake up every day. I thank Him for allowing me another day in this sewer we call earth, but one day I will not wake up. That is when I will see what true beauty and excellence is. I will be in His presence for eternity. Until then, I will understand that He can do what ever he wants to do, because He is God.
I am but a creation that He made, and He can snuff me out at anytime He so chooses. Now he tells us in His words that He will give us every chance to accept His Son before our time is up, but ultimately it is our free will choice and with it come all the consequences that follow.
Until you truly accept that fact, you will forever fail to understand just what kind of blessing your life is, and when you do you will understand that anyone who dies in this world had the same chance.
As for children, well, they are always in Gods hands, and if they die early then they are spared the suffering this world brings to those who live a long life.