Judging from my own anecdotal experiences as someone who "doesn't look like a German", i'm willing to take a wild guess why: Because everything they do is under a microscope.

I got my bags searched, because i "walked suspiciously through the isles" in a store (woman thought i'm a foreigner) and i got a false accusation by a police officer who said he "knew people like me".

Also the German BKA crime statistic, as an example, shows reported crimes. It doesn't exactly show how many where actually convicted. So i guess i'm also somewhere in the stats from a few years ago.