Most companies do not want to reveal why they have their pricing structures the way they do. In this case, looking at the 10x model, they have a much different eyepiece housing that is not standard for excepting magnification, so this is a specific model that is made separate with separate parts, therefore causing more time and money to make. The turrets are still finger adjustable, just shorter with the base thread to except covers. Once again, these are separate from the other Mk 4 scopes
and cost more time and money. As for why they have covers and the other models don't I do not know that one. I can only speculate that a 10x is still popular with hunters and target
shooters, and hunter demand covered turrets. opposite side of that, operators that crawl around and bump everything sometimes want their turrets covered or protected from movement if they don't have a lock.