This isn't always the case - take for example the "CTI 2.0 or Higher Settings" section under Setup --> Customize --> Call Center --> SoftPhone Layouts --> Edit --> Inbound Calls.
This is what I was seeing:
According to the documentation, "This section only displays if your CTI adapter was built using the CTI Developer's Toolkit 2.0 or higher." While working in a client's Org, a 2.0+ CTI adapter was being utilized in both their sandbox and production Orgs. Within their sandbox, I was able to see this section, whereas in production, the setting was missing.
Naturally, I wondered if it had to do with release differences, but the sandbox was Spring '14 and production Winter '14.
Setup-wise, they were identical with one small difference - my user account was no longer listed as a User under the Call Center's settings (Setup --> Customize --> Call Center --> Call Centers --> Click on the Name --> Click on the "Manage Call Center Users" button).
Once it was added back, voilà! The "CTI 2.0 or Higher Settings" section was back.