I grew up in Northern Califonia, in an area where many of the landholders were what we called "Italian Swiss", who were from the far north eastern part of Italy, formerly ruled by Austria. Many of their tenant farmers (the people who actually waded around in cow manure all winter long), were Italian Americans from Calabria and the provinces south of Naples. All of these folks prefered 16s over any other guage, at least all of the first and second generation who came to the US before WWII. After that, many of them had served in the US service and wanted all things purely "American" meaning, in this context, 12s and repeaters, not 16s and doubles. But there were plenty of people around when I grew up in the late '40s and '50s who thought a double barreled 16 was just the only gun a man should use.
Shotguns were used primarily for hunting California quail in that time and place; every other use was secondary. Kids started with single shot .410s, period, and graduated to 16s, (and later, 12s).
20s were for women, experts, and eccentrics, and there weren't many of them hunting. I never saw a 28 until the '60s, and that was on a skeet field.
