Thieves are not educated enough to understand the difference and will steal the fiber and try to sell it (with no success) and in the anger, destroy huge swathes of the remaining fibre.
https://www.ghanaweb.com/GhanaHomePage/NewsArchive/BNI-disco...
In any case, the fiber situation in Ghana was dicy for a time because theives were cutting the fiber lines in hopes they were copper. Thieves are often in a hurry so they cut first, check, then move on.