Let's be more specific.

Microsoft didn't like the fact that Munich switched to Linux, so they moved their headquarters to Munich to gain political clout, ushered in a more favorable mayor, and then hired Accenture to release a report claiming that Windows would be more cost-effective.

It worked.

https://www.techrepublic.com/article/linux-in-munich-no-comp...

Most likely there were just bribed by one unnamed company, or promised some investments - the time correlates with expanding their office in Munich. So I would not trust Munich's claims at all. Despite recent whitewashing of Microsoft image they were never practicing a fair business.

If you read some more about the issue, it becomes clear that after an election, the conservative party with long-term ties to Microsoft was happy to reverse the decision.

But they said their problem was that they also needed Windows machines to run line-of-business apps and that it wasn't cost effective, something that Wine is supposed to help with (running Windows apps in Linux).

Turns out, using something other than Windows doesn't equate to using something that requires no support. And support is not free.

Irrespective of what system is in place there will always be support/training/running costs associated with managing a big IT system.