Ah, I see your angle here. Well, here's the thing. If God were to prevent all evil from happening at all times, free will would be non-existant. In other words, it would never have been given to us in the first place.
What you're asking for would amount to people being like robots, pre-programmed to never do wrong, to only do good. Or marionettes who only do what the One pulling the strings wants them to do.
Obviously God didn't want that, as that would be pointless, and wrong. And a waste of time. Which gets back to why I said that God wants us to trust and love and obey Him WILLINGLY, not because we were pre-programmed to and have no choice in the matter.
So you can't really have it both ways. Either you want free will and accept that there will be some evil in this world.... Or you are basically asking for a world of robots or puppets on a string.
If you really want a world with no evil? Well, there
will be a world like that one day, in the New Heaven and Earth. In Revelation, it says:
"He will wipe every tear from their eyes. There will be no more death or mourning or crying or pain, for the old order of things has passed away."
But you have to be reconciled to God to get there, you have to be born again.