I do not believe that the definition for operator dependent that you provided is correct, not in a modern medical context.
Operator dependent refers to variation in results due to medical technologists use of diagnostic equipment. It is important for the clinician to be aware of such "operator dependent" variation. It helps ascertain whether deviation from an expected ("normal" or baseline) result may be etiological (and thus due to a disease process), versus deviation that is caused by the technique used by the diagnostic technician.
Medical imaging, EEG's and EKG's are subject to operator dependent results. The abstract of this paper describes operator dependent variability in diagnostic imagery of the heart:
The purpose of this study was to evaluate variability in the
quantification of myocardial perfusion images obtained by a group of
experienced operators using two widely used programs... The large
variability... may influence the clinical interpretation and cause false
In the prior example, the operator was a skilled technician. The operators may be physicians. In this example, the operators are radiologists (all are M.D.'s):
We sought to assess the reproducibility of size measurements of small
lung nodules examined with [tomography]... Three radiologists measured volume and
diameter of 20 phantom nodules and 37 lung nodules... Operator-dependent variability
of size measurements of small nodules is not negligible and should be considered in
lung cancer-screening studies.
Connotation of improper technique or lack of skill is not necessarily associated with operator-dependent results. Sometimes it is, as well as the usability design of the testing device itself. This study compared the effectiveness of mammography versus ultrasound and MRI, and found that ultrasound had the same rate of false negatives due to operator-dependent error as the other two methods.