IAS 8 Accounting Policy, changes in accounting estimates and errors

Why is a change in the measurement basis of a non-current asset out of the scope of IAS 8?

For example a change in measurement of a non-current asset from historical cost to fair value or replacement cost falls under the scope of IAS 16 but would not require a retrospective adjustment under IAS 8?

The confusion arise as the official Kaplan text gives an example the a change in accounting policy would occur if there is a change in measurement basis e.g. stating assets are valued at historical cost rather then replacement cost. But the Test your understanding question does not agree to this as it says a change in measurement of non-current asset from historical cost to fair value will be treated under IAS 16

Clarifications are welcomed