Part of the costs of a park is cleaning up after people, its already in the budget. So is the landscaping. So is the coverage for wear and tear in general.
Its also funny to see the difference. National Park Service embraces Pokemon Go and enjoyed the increased park traffic. Austin embraced it and stores all over downtown and even government buildings had specials for Pokemon GO'ers (some public art museums here gave like 50% off admission if you were Pokemon hunting)
And the fact that so many normally sedentary people were getting up and going out and doing shit and getting exercise .. and people still went out of their way to be dicks about it... I don't get it.
Aside from Niantic's handling of the game, its PR and its issues, the pokemon GO craze was probably one of the most positive, healthy things to go viral in a very long time in the US...