Before 1990 British politicians were fond of boasting that 'Britain's National Health Service is the envy of the world'.
By 2000 it was generally aknowledged that public health care in Britain was much worse than in most countries with a comparable level of per capita GNP. Politicians therefore began looking at how other health care systems in Northern Europe were operated. They found that, although healthcare was publicly available free at the point of delivery, there was much greater diversity in the ownership and management of facilities. Similar considerations apply to 'public' parks. Public accessibility is a defining characteristic, but there is no need for 100% public ownership or 100% public management. Quite the reverse.
The principle of subsidiarity should be rigorously applied to public parks. In the European Union The "subsidiarity principle" means that decisions must be taken as closely as possible to the citizen. National Parks should be owned and managed by the nation. Local parks should be owned and managed by the locality. But ' locality' does not mean 'municipality'. Subsidiarity can go way below the municipal level.
The subsidiarity principle can be applied to public parks, quite simply, by letting local organisations have control of the money which the municipality has allocated to a particular park.