1: At some point, we learned that the scope included on all of the Akaku that we have seen were added after they were made. This is to compliment the mask's power. What this means, though, is that the base akaku that most matoran walk around with in the MU has no scope.
2: There are, to my memory, four characters in the story with scopes built into their masks: Kopaka, Nuju, Kazi, and Matoro. Ignore the MNOG2 matoran.
- Of course whoever made Kopaka's mask added a scope. He was a Toa, and his Akaku actually had power. It made sense for him to get all the "Extras".
- Nuju had his scope build extra, since the scope really does not necessarily compliment the Matatu's power. It makes a lot of sense for Nuju, though, who actively used his scope in his role as a scholar (you actually see this too in LoMN).
- I can't really explain Kazi's scope, but the guy came out of Karzahni. If he had a third arm coming out of his forehead it would make sense.
- Matoro's scope, however, makes no sense. What little we know about his time in Metru Nui confirms that he was a scholar like nuju, but that seemed to be an "on paper" job at best. It seems like his main job and focus was selling rahi, and spending time in the archives. Not exactly the kind of thing you'd need a scope for. Once the move to Mata Nui happened, he was a translator. Being able to see a mile away won't help listen to a guy three feet away from you. Basically: unlike the other three, Matoro's scope makes no sense.
- Maybe they were very common additions, given to almost anyone. This is not likely. It would explain why Matoro was able to get a scope, BUT: it meant that there is a short list of characters who we know, who therefore WOULD have a scope. Vakama, for example. If scopes were easily obtained, then Vakama literally had free access to the materials and hardware to attach a scope to any mask he wanted. He would also be able to make use of it, finding microfractures in masks he made. TL:DR: if scopes were easy to get, Vakama would have a scope. Vakama does not have one.
- Scopes were hard to get. If this were true, then Matoro would absolutely "not fill the requirements" for acquiring one.