Why would they need to if God was looking out for them?
God gave man dominion over his creation and ample resources to care for it appropriately.
If we know clearly that some aspects of that creation are both necessary yet extremely powerful why take a chance when there plenty of far less dangerous options?
People love posting memes with images of the starving in Africa with some "witty" remark about God's failure. Well, the US alone produces enough food to feed the entire earth many times over. Why then are folks starving?
What God didn't give mankind was a promise that folks will never stub their toes or break their arms or get the flu or lose their lives.