It is free bc it is partially funded by the gov but it needs to fundraise the difference. Memberships and parking is/was one of the fundraising streams. The large events raise money through corporate sponsorships (for instance you might remember seeing Pepco’s name at zoo lights) and some of the evens (like the Halloween event) raised money through ticket sales. 3rd party/outside vendors set up along the main walk prob shared their profits as another revenue stream for the zoo. So, it makes sense that it all took a hit during peak SAH COVID. But the Smithsonian is not doing itself any favors with the way it handled dissolving FONZ - in terms of how it treated the FONZ employees and the visitor experience.