So--You have first hand experience at those institutions I mentioned?
I actually installed and configured the clustered computers running linux at those places. None of them were using Windows for their main work.
I seriously doubt that you got to see everything they do in those (large) companies and institutions. You are making it sound as if all large companies and instutitions used Linux for all their work (except desktop workstations). That is a preposterous claim. Maybe some of them have a project for which they experiment with Linux, but that doesn’t mean that nobody uses Windows. You really think that nobody has a Windows Server installation running SQL Server? Or Oracle? Or Exchange? Or Sharepoint? Or any of the usual enterprise software systems?
I visit the CeBit every year, checking out each and every booth in the enterprise software halls. It is mostly Windows. Linux is the total exception. To think that all these companies are only pretending to sell Windows software, and their customers are only pretending to be interested, while they are really running all Linux software in their companies, is absurd.