[QUOTE=Pygmy Rugger]
[WAG]Beers and wines use different yeast strains. Perhaps the alcohol is slightly different molecularly, or, since there is less “filler” (non alcoholic portion), it is able to get into your bloodstream more quickly.[/WAG]
[/QUOTE]
Sorry, I can’t see any way in which this is true. Ethanol is not a variable thing. Any variations would be different organic compounds, most of which are toxic. The fermentation process is a very predictable process.
The most likely explanation is that the high school drivers ed equations you quote disregard some important variations. The most important of which is probably variation in the volume of a standard glass of wine.
Most bottle beers are 12oz, or 11.2oz for European imports. Excepting Belgian strong ales, most non-light beers have a %ABV between 4.8% and 5.5%. Light beers are as low as 3.8%. So the equivalences you quote will change if you are drinking a light beer, as most people tend to do in the US. Thats part of the reason why the 2 beers = 2 wines would tend to make the wine seem more effective than you expect.
As for wine, like most things in the service industry these day, portions have ballooned. No longer is a 5oz glass of wine reliably standard. Most restaurants use huge, wide mouthed glasses for their wines, especially reds, and controlling the portion size is a dicey proposition. I would wager that the typical restaurant portion of wine trends closer to 7-8oz, and that inexperienced wine drinkers pour even heavier at home were presentation and profit margin aren’t important. A 5oz glass of wine would look practically empty to many people.
Lastly, wine, as already noted, varies even more than beer in it’s alcohol content. Often trending towards the stronger in now popular styles such as Merlot and Cabernet. The typical range can vary from 8% at the low end and 16% at the high end.
Doing the math, a 12oz beer at 5%ABV contains 0.6oz of ethanol. a 5oz glass of wine at 12%ABV also contains 0.6oz ethanol. While the amount of alcohol in the beer is going to be very consistent, and any change likely being less alcohol due to a light beer, that amount in a glass of wine has a ton of variability. A strong wine at 16%ABV poured tall to 8oz is going to balloon to 1.28oz of ethanol, over double the alcohol content. Suddenly two glasses of wine becomes the equivalent of almost six Bud Lights.
In short, beer and shots are very consistent in the portioning of alcohol. Wine lends itself to a huge degree of variation, hence people accidentally over serve themselves with wine.