The important distinction is congestion. Users should pay auction prices for contested resources (how much someone else would have to pay to get access). Windfall gains should then be used for general welfare spending for the community (maybe building more of the scarce resources). This is how shared infrastructure can finance its development, in a way that incentivize efficient use age patterns (smoothing/flattening the demand across time)

Marginal cost of a non-fully -occupied library is approximately zero.