The basic problem is that many managers are not ‘hands on’ or ‘on the floor’. They sit in their cushy offices and take reports from ‘people they trust’.
In many cases, people they trust have their own agendas.
They may be stealing and blaming others, they may sneak out early, and need to get rid of other eyes. They may be running their own rackets, because they know the Manager is too comfortable in the office to come out and see for him/herself.
So perfectly good workers are discharged and replaced by those who ‘owe’ the supervisors so would cover up for them.
So honest worker are daubed with stealing because the supervisors need a scapegoat.
Being physically on the floor, where one can actually see what is happening, and get a familiarity with procedures is vital for a strong business.
The Manager should ‘normally’ be wandering around the business, not leaning over the shoulders and making it obvious they are spying.
One should, as a manager, trust no one. One keeps that quiet. A good manager acts as if s/he trusts the staff, so that the honest staff feels vindicated and the dishonest staff thinks the manager is an idiot.
The dishonest staff will be caught, the honest staff, avoid suspicion,just by the Manager being there, really there.