The wide-spread acceptance of evolution in the west is because of lack of another explanation of how life must have come into existence when you cannot bring yourself to give any possibility to a supernatural creator. The same people who would fume when you mention a god will very happily accept an assumption when the word "science" is attached to it.
Just because we can observe mutations doesn't in any way prove evolution in a macro level that results in speciation. Yet it's treated as fact by so many without even knowing enough about it. An average person's acceptance of evolution is no different to a religious person's acceptance of a creator, no matter how much you'd like to think otherwise.