Scientists have an amazing amount of faith. This independent verification you speak of, is simply another method to be trusted. There is no evidence that something is more likely to be true simply because many people investigate it. It could be the case that the more people investigate something, the more likely they are to draw false conclusions. Observations which seem to reveal facts may simply be illusions. Also, they completely trust that past events cause future events. In reality, we only observe the present. See scientists are so deeply absorbed in the game they're playing, that they are unable to think scientifically about the scientific method.