Please keep in mind that these pools were likely built during the New Deal era, meaning that funds were available for so many different types of public works.
Seriously, look at any of the buildings in your community that were built between 1900 and around 1970. Would any community be able to afford to build those now? All the marble, granite, steel, rought iron, leaded glass, etc. etc.? That pool is but one example, and is not a sign of largesse by any stretch.