(group) A frequent argument in support of government-produced goods is that they are vital to social welfare and therefore their provision cannot safely be left to the whims of the marketplace. Does this explain why parks and libraries are usually municipal services, whereas food and medical care are usually secured through the market? Can you suggest a better explanation to account for these cases?

It's hard to prevent the free rider problem in the case of parks. Keeping non-payers out might ruin the experience of the payers. And then no one would pay. Access to libraries can be more tightly controlled (because they are indoors), so this might be more of a case ofpandering to voters desire for a free lunch than anything else.