The point is that the pilot has a (very) vested interest in getting it right to the best of his/her ability, as opposed to simply being a disinterested bean counter in a back office somewhere (and who doesn't have their life on the line). Combined with the fact that pilots have more aviation knowledge than most pax, it gives us a very good reason to trust their judgment. Nobody said they are perfect -- if we expected perfect safety, nobody would ever fly...or drive...or chew gum.