This is purely a function of the supply-demand curve applied to localized and regional markets. Add in goods and services inflation and you have a prototypical tight market.
Golf grew substantially in COVID and continues to grow organically, albeit at a slightly slower rate. Why?
It's now an activity endorsed by a younger generation, one that has experienced (even if tangentially), the widening funnel of off-course golf (i.e. golf entertainment: TopGolf, PopStroke, alt media brands (NLU, Foreplay, Good, Good). Short courses, especially lighted par 3's like Grass Clippings, soon-to-be-launched Playground Golf, etc.. are also contributing to the underlying organic and demographically-shifting growth of the game. The growth of off-course golfers, according to the NGF is outpacing the growth of on-course golfers by nearly 2-to-1. Women are also growing their initiation and participating rates faster than men. Even LIV is playing some small role in attracting a younger audience.
Private clubs are recognizing this phenomena and re-setting their facilities and services accordingly. As an owner of several clubs, I'll testify to the fact that women are now making the joining decision on equal footing with their male counterparts. They want a safe, centralized, socially-comfortable place to center their family and sporting life around. Younger people with means want a more relaxed and fun-loving club that will tolerate somewhat looser hospitality constructs (i.e. jeans in the dining areas and music on the course) than their parent's clubs.
Golf and country clubs are especially attractive in areas of strong family formation and approachable residential markets. All of this is highly localized and responsive to regional economic conditions. A testament to this is most rural or exurban clubs have not been able to raise their initiations or dues nearly as high or fast as more desirable ones found in more densely populated areas.
Initiation fees at clubs are an economic calculus equation of who the audience of current and future users are. Club finance, for most places, treat initiation fees as cheap capital designed to augment or replace debt for current and future capital expenditures. Dues are a function of meeting yearly operating budgets. The combination sets the pace for 3,5, and 10yr budgets.
With long waiting lists and golf's current and safely-projected popularity, it'll likely take a deep recession or economic shock to break this trend.