Oh the horror!
I've visited some areas in the southern U.S. where many neighborhood bars have oversized cue balls, but the bars where they have league and serious players will of course have same size same weight tournament balls.
Up here in the Pacific Northwest, *every* single bar has same size same weight cue balls. (At least in my area.)
The only thing I can figure out is it is the weather. Up here we have bad weather a lot of the time and people find indoor activities to keep them busy. Thus the better equipment. Down south they have good weather a lot of the time, so maybe they don't play pool as much?