Almost all problems like this can be solved by improving an application data model, but here’s the thing, lots applications have dodgy data models, either due to time constraints, or because the application evolved over time, and the data model didn’t. So these are all real world problems and examples, but creating a “simple” problem to demonstrate the issue almost certainly means also creating an example where other “obvious” solutions exist.

Just because you can’t imagine how this simple example might represent a much more complex “real world” problem, doesn’t mean it doesn’t exist.