hence, when you work in an international company, the ability to speak some random language natively that nobody has a definitive use for shouldn't have any impact on your salary.
Fuzzy, with all due respect, I don't think you quite understand what these jobs are.
They're normally outsourced jobs in support roles - so knowledge of the target language is absolutely essential. Yes, many Dutch people speak good English, but support jobs by their nature require the support to be in the native language. This is why native speakers are getting a premium for the work - their language is absolutely spot on. There won't be issues with miscommunication and so on - hence they can command a higher salary. It won't be native speakers getting extra as such, it will be anyone with a C2+ understanding of the Dutch language.
English may rule at the higher levels, but in support positions, the target language is absolutely essential. Mr Dutchman who needs his schedule organised will want to speak in his native language, not in a foreign language, hence why these jobs exist. Let's not forget that the Dutch who are getting the jobs done for them may also not want to speak in English - why should they? They may not even speak English - what use would English speaking support staff be if they can't even communicate in Dutch?
And from what I've seen, international companies still have a heavy use of native language.