A new government now, that want to make it totally open again.
It’s the ‘Norwegian tax administration’ that give out the information.
Media always have full access and can write articles based on it for individuals or groups of people, as long as they don’t publish the whole dataset.
So, why not publicise the performance metrics of the employees as well? Not public at least accessible like what you mentioned on salary. I'm not questioning why Norway isn't doing it but in general why not?
Such access to performance can also serve as a driver in the employment industry. Along with the engineering blogs, one can display links to the portal with company attested achievements and stats, it will at least reduce false claims in LinkedIn.
I don't think I know of a single manager I've worked with who would have been as honest in performance reviews if they knew their feedback wasn't going to be confidential.
All of that is to say I wouldn't put much, if any, stock in such information.
More often than not, the sum of individual performance is not 2+2=4 but more like 2+2=3 or 1+1+1=4
Combining high performers (2) is often not better (1)