First of all, I have to praise this community. The fact that so many people took the time to answer me is just amazing.
He usually uses his shotgun for hunting deer and such. However, what you guys said made a lot of sense. There is no point in mounting a scope on weapon with such a range. My friend just witnessed a couple of time people making really long shots kills with it, so he figured a scope could help a little. But even if those stories are right, I think human skills is a key factor in such shots. Calculating bullet trajectory and all sort of complicated things. But it stands to reason that a scope in this case won't help anyway. I guess he just thought it would look cool on them.
Thanks again everyone. Sorry for not contributing a lot. I'm a firearms enthusiast who doesn't own any guns. I like to watch and read a lot of firearms-related topic, but that's all. Weapons are not legalize here. Only hunting shotguns. And they're very expensive. I won't lose my love to guns though, things may change someday.