I'm not saying there's no corruption in Germany - I think there's always going to be some level corruption at a certain scale of state - but there's no need to go as far as China or Russia for comparison. Just come to the South of Europe for a taste of what grand-scale corruption in what are otherwise (seemingly) high-functioning democracies...
I remember watching a Brazilian high government official (Justice minister?) on Anderson Cooper mentioning that Lava Jato had seen ~3 USD billion disappear, as Cooper reacted with a wide-eyed grin... And I thought to myself, huh, that's arguably the largest national corruption scandal in Brazil in recent history, and it's about the same size as the "EREs case" [1] in Spain, which was a regional affair, and where ~3 EUR billion also disappeared. One of many perpetrated by both main political parties in the last couple of decades.
Like I say, I don't think Germany is without corruption, but it's a matter of gradation - it's hard to label it as an "insanely corrupt" country seeing what's out here.
[1] https://es.wikipedia.org/wiki/Caso_ERE_en_Andaluc%C3%ADa