I had a feeling this was going on after looking into starting a liquor company with some friends. There are several large manufacturers producing all types of alcohol (whiskey, gin, vodka, etc.) and selling in bulk to bottlers. This is likely how some of the lower end alcohol producers operate, but I'm sure there are plenty who use fancier packaging to upsell their product.
A good half of your vodka brands are just repackaging ADM or the local equivalent farm waste ethanol with water local to the bottling location (and maybe extra distillation or filtering passes if you're lucky).
It's the bottled water business model, but swankier.
Even Hangar One, a favorite of mine, is at least half neutral grain spirit from industrial farms. Thankfully they re-distill it with pot-distilled grape vodka, which rounds it out (no rubbing alcohol flavor).
Dave Arnold on Cooking Issues tells a story from when he ran the tech program at the French Culinary about buying pure potable lab ethanol and diluting it down himself for "perfect" vodka at a tiny fraction of the price.
