What if they make 59,500?

You could use interval notation to disambiguate e.g. [50k-60k)

https://en.wikipedia.org/wiki/Interval_%28mathematics%29#Not...

You're right...I completely forgot about that. However, the "explicit" way it's written above is easier to understand in my opinion.

While you technically have a point, I would have thought the target audience (developers) would "naturally" interpret this as a closed, open interval as remarked by another commenter.

I'd argue that your suggestion is not right (again as pointed out by others) and not natural as you claim.

If we're getting into semantics this also wouldn't be accurate since someone can earn $59,500. I think most people that earn x0,000 will pick the larger category that they fall into meaning the results should be fairly accurate.