A self supporting park might be a lot more availible and well maintained than one that rund down , runs out of money and closes.
The origional problem was a drop in some Citys revenue , if tax income goes down for some reason should the parks be closed , or sell the trees?
BTW some trees produce lumber at about $1000 per tree , can a city plant its back lot with Walnut and Cherry to produce a harvest for money twentyfive years hence?