Is IAS without instrument error the same as CAS?
Even without instrument error, IAS does not equal CAS. This because there are two kinds of errors that make up the difference between Indicated Airspeed (IAS) and Calibrated Airspeed (CAS)


Installation error
Instrument error


Installation error is basically a pressure error. Airspeed measurement is a measure of dynamic pressure of the undisturbed airflow. When the pitot tube is not placed directly into undisturbed airflow the IAS will not equal the CAS. Another source of installation error are leaks in the pitot system. 

Instrument error is the error introduced by ASI itself by transforming the pressure to a speed indication. For example calibration errors of the pressure sensor or excessive friction in the mechanical drive system of the dial fall into this category. 

The POH in your example assumes no Instrument error, but is corrected for installation error. An implicit assumption is made that there are no leaks in the system, so the POH corrects for airflow disturbances. That is why some aircraft have different tables for different configurations; the configurations affect the airflow around the pitot tube.

In aircraft equipped with electronic Air Data Computers (ADC's) the installation error is sometimes automatically corrected by making use of angle of attack sensors, electronic configuration information and lookup tables.