Depends on what you’re evaluating the candidate on. If you’re evaluating the candidates ability to reason through a problem, and communicate the reasoning, the. GPS is arguably a better question for a software engineer as they’re unlikely to have studied it. Thus you can watch them work through a problem they haven’t thought about before, but which should probably have the basic tools to solve.

There should be no expectation of them coming up with the “correct” answer. But they should be able come with an answer and explain it clearly, warts, holes and all.

Using something real like GPS also ensures that the candidate understands why the problem is a useful problem to solve, and what the objective of the solution is I.e. a system that lets you locate yourself on earth.

Only reason I can think of is it is a real world example of distributed coherency/information problem and if you squint hard could give insights into things like paxos (and why it does what it does), why certain types of keying/sharding/distributed computing are done the way they are done.

But directly talking about those topics is probably handy.