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".
Yeah, not to make light of the tests, but those degrees boil down to paying Goethe Institut to take their classes that prep you for the test.
I have a degree from a German University and don’t have C2. That requirement can be interpreted as “must not be an immigrant”
> Most Germans won't be able to pass a C2 test
That's not true, but it is a commonly shared myth. I've taken and passed C2 with the highest mark in every category (I moved here when I was a young teen, wanted to know if I would pass it after hearing years of people saying things like you're saying).
Most Germans would easily pass C2, although I think they'd have to be well-read/possibly university educated to get high scores (mostly need to be able to read quickly, give a semi-structured presentation and write a persuasive essay).
For what it's worth, I could run linguistic laps around all the other test takers there that day, and I assume at least some of them passed.