Re 1: the "average" may not matter all that much. The study's suggested 2 drinks per day is the same as the American average, which according to some web sources I found is 1.94 drinks per day (among adults). [1]
The difference may be that the variance is not that high. 16% of Americans binge drink [2], which drags the average up - a significant plurality doesn't drink at all. The truth in this case could be consistency. No binge drinkers, a consistent level of wine purchasing indicating a high level of wealth in the community.
Looked this up. A standard serving of wine is 5 fl oz. Two servings a day makes 10 fl oz, and let's say we're talking about a household of two adults for 20 fl oz. At $20 per 750 mL bottle, that's $15.77 a day or about $5757 a year. I think that's well beyond the range of affordability for the median household, even in wealthy countries like the United States.
The difference may be that the variance is not that high. 16% of Americans binge drink [2], which drags the average up - a significant plurality doesn't drink at all. The truth in this case could be consistency. No binge drinkers, a consistent level of wine purchasing indicating a high level of wealth in the community.
[1] https://www.usatoday.com/story/news/nation-now/2017/12/28/ho...
[2] https://www.cdc.gov/alcohol/data-stats.htm