I am wondering do we really need to put a sign for you to clean up after your dog?

The other day we were walking our dogs and some guy came out of the building with his huge great dane dog and crossed the street to the green area and he stopped by the walkway and let the dog go to do his business, it just take 5 minutes or less and the poor dog did his business and they left!!!!  OMG I was in shocked! the guy didn’t clean up after his dog and didn’t walk the poor baby! This is not parenting guys , your dog need more attention.