In general, the longer the employee handbook is and the more convoluted it is in its rules of do's and don'ts, the more that you can be assured that the stuff in there is primarily for the benefit of the employer and certainly not for the employee. For example, those in the field of apartment or housing leasing, and those in the fields of restaurant service, are depending upon the employer of such, subject to being "shopped" by an outside party. The meaning of being "shopped" is that a paid consultant comes into the establishment as a "customer" or potential customer, and proceeds to record the conversation of the interaction between them and yourself, with a report being written, and video/audio footage being submitted to the employer who contracted with them. The purpose of the whole "shopping" experience is not some sort of pretend exercise, but to receive valuable feedback in the "real" world as to whether one's employees are following the company procedures on how to properly address customers, their response to customers, their professionalism, and the overall experience being in conformance with company priorities and standards.
You might think that none of this is really necessary if the Manager actually did their job, and periodically monitored conversations, and did follow-ups on "traffic" that came into a property or to a restaurant, but apparently that isn't good enough, so an "independent shopper" is hired instead, which, because such an interaction, involves real consequences, can mean the loss of one's employment, because your "shopping" score is too low, even though your previous reviews have been positive, and/or the general perception at the company is that you are a good employee. The fact that any one score could cost you your employment as well as the fact that you can be shopped at any given time, just adds unnecessary stress to a job atmosphere which isn't really necessary. That is to say, if the abiding point of "shoppers" was to critique and improve employees as necessary, ultimately resulting in a meeting in which there was a give and take between employer and employee, that would be one thing, but it's an entirely different thing, to accept one survey and thereby terminate or suspend the employee as if that one experience is the summary judgment of who and what they are within that company.
While it is understandable, that when a company is not meeting its sales targets or profitability, that it may see the logic in receiving an independent feedback from a "shopping" company, or periodically to request to be "shopped" in order to confirm that employees are performing per the standards of the company, the fact that the "shopping" is setup to go after the employees specifically, but seldom the managers of such, and therefore does nothing to address poor training, poor work atmosphere, and poor exemplars by management, demonstrates that even when a "shopping" experience determines that an employee is not meeting the standard, doesn't necessarily resolve a thing, for if the management and training by a particular company, is fundamentally poor, than the employees will often reflect that in their performance.
Sure, "shopping", may have its place, but the reality of it is that a management that gets to know its employees, that cares about its employees, and that walks that place of employment to observe carefully interactions between employees and customers, will learn just as much or more, than a "shopping" experience can ever really deal with, for good management works with its employees, rather than relying on a version of subterfuge or intimidation in order to keep them in line.