There is ALWAYS collateral damage in any military operation. With your philosophy it would be impossible to defend oneself from an enemy as you could never ensure zero collateral damage - especially when your enemy uses human shields. You are most certainly welcome to espouse that philosophy and I wish it was the way all humans treated each other! But in a world where one side will attack, rape, behead, pillage and use innocent human shields your philosophy is extremely naive. It would be the end of Israel as a state.
In saying the above I am NOT condoning the latest refugee bombing, it certainly sounds horrific and I strongly believe Israel must go to greater lengths than Hamas has shown to minimize innocent casualties. But I will also wait a few days to get a full account/judge this action given the exaggerations/misreporting from the hospital bombing a couple weeks ago.