Costs-by-cause principle/polluter-pays-principle that's called in the laws.
Thanks for mentioning that - wasn't in any German paper (only in the "press map" of the Border Police* and the local
advertising weekly
*Actually, this was a job for the "Federal Border Police", since the dung was left on railway ground - and the the Transport Police is part of the Border Police :wink:)
Wuppertal, btw, is a "town" of 370,000 inhabitants and home of the world famous
"Schwebebahn" (= unique suspension line across the valley of the river Wupper).