It may not sound like a satisfying answer, but: because I'm not here to earn a language certificate but rather to live and work, my German is more than fine, and I think my time could be better employed doing something else.

I've worked in German institutions for a long time now, I've published in German, I have no problems understanding people and, leaving my accent aside, people can understand me. I read books in German and understand German movies. My German is fine.

I could take time away from learning what's new in tech and science (a lot, apparently) to get a C2 but, and I may be wrong here, I don't think someone asking for "minimum C2" (which, again, disqualifies even native Germans) is engaging with the process in good faith.

I have no objections to learning the language, which is why I've done it. What I do object to is chasing a pointless certificate when I could be doing the thing I was brought here to do.

As a inverse example: a (German) family member has lived fully immersed for 20+ years in my Spanish speaking country.

I doubt he could pass a C2 level test, there's simply a hard limit in language learning for most people without academic instruction. It's also pointless, he's had a long career in a professional field where clear communication is mission critical. Furthermore even if another foreigner with a shiny Spanish C2 certificate appeared they would fare worse, because they wouldn't know the local social minutia.

Aside from jobs in the Literature department or something, a C2 requirement is a "foreigners need not apply" sign.

Just ask Mark Twain ;)

https://faculty.georgetown.edu/jod/texts/twain.german.html

C1 can be achieved (I did it on 360 hours). C2 is academic level of language proficiency -- you have to either deliberately study for the difficult exam or get an university degree in German. Most of the Germans won't be able to pass a C2 test.

When a company sets C2 as a requirement, it can be interpreted as "must have a degree from German University".