You provided a real example (tracking field workers) so I'll happily answer from my limited but real experience with field worker management software.
This solution allowed merchandisers to task, schedule and track their field workers to make sure they were attending to routes in the right order, doing everything correctly and generally following instructions. The consequence of their not doing so was incorrectly or unstocked products, and product not being sold. Fraud was also a problem, as they prior to mobile software they had field workers gaming the system in different ways.
So their objectives, or what the business needs, included:
- Keep field worker costs under control by eliminating time fraud
- Get the products merchandised and presented as specified
- Keep the store shelves stocked with more product when it sells out
Expressed as requirements:
- Ability to know where workers are while on the clock
- Ability to known how long field workers' average store visits are
- Ability to schedule worker visits according to most efficient routes
- Ability to know whether workers executed on the instructions given for a location
In UX, it's definitely in your best interest to understand business objectives because you otherwise might not be solving the right problems.
Requirements are how you define the criteria to fulfill an objective. In UX, you can think of it as the description of what design needs to accomplish.