the inadequacies of job descriptions

At the beginning of his popular presentation for TED, Barry Schwartz outlines the job requirements of a hospital janitor. He points out that none of these requirements mention anything that involves other human beings, yet when janitors were interviewed by psychologists, much of their work involved human interactions and a degree of improvisation and 'practical wisdom'.

I was interested in the job requirements of hospital technicians who may be dealing with pneumatic tubes, and came across these job advertisements for a lab tech at Ochsner Health System and a diagnostic scheduling technician at St Luke’s Health System:

Lab Tech: Gross Room, Ochsner Health System

Duties: Accessions surgical cases, biopsies and autopsy specimens from various departments, and clients via Central Specimen Receiving (CSR), the train, pneumatic tube or courier. Verifies patient’s demographics, accessions patient information and test requested in Laboratory Computer. Accurately labels specimen containers tissue cassettes with assigned number. Assist Pathologist and residents in the gross dissection room. Maintains record of Gross Room workload and data entry. Records all specimen errors or discrepancies. Performs staining, autopsy specimen procurement under direct supervision by a Pathologist, Pathologist Assistant or Histopathology Supervisor. Demonstrates actions consistent with Ochsner Expectations as duties are performed on a daily basis.

Diagnostic Scheduling Technician, St. Luke's Health System

Duties: 7. Operates medical center equipment such as computers and software, phone systems, paging systems, intercoms, fax machines, copy machines, pneumatic tube system, and printers in order to perform the duties of the job. Accept change in a positive and professional manner while willingly learning unfamiliar tasks.

Whilst the job descriptions do mention work with other people (I have only included a section of the second job description), they do not explicitly describe the work that I am interested in: the adjustments, the ‘repair work’, the tinkering that technicians perform to get their work done. There are hints of this buried in words such as ‘record discrepancies’, ‘accept change’, ‘learn unfamiliar tasks’, however so much is left out. Although when does a job description ever really describe a job?