I think you will find that proof is found mainly in a math class. Outside of that, we tend to rely on evidence that seems plausible.
But that is not a bad thing, if we demanded proof for everything, we could not function in the world. Our worldviews, or belief system, is the matrix through which we make sense of what we think is the reality around us. Through this worldview or belief system, we not only categorize what we think are "facts", we assign those facts value. Then we make decisions accordingly.