A common form of central heating, like burning fossils kind that delivers hot water over insulated pipes to each building, is more efficient in pretty much every way and is cheap to add during building construction than doing it individually. But it's not the case with a "central AC", it's less efficient, more expensive to add during building construction and operating costs are no better. Just think about it, you can't just deliver cold over a pipe and rely on air convection, like with heat, you need to literally move cold air into each room and make it individually adjustable. It's a ridiculously inefficient complicated expensive system requiring extra space and with installation costs higher than that of all AC units individually installed.