Jeff, sorry for baiting you, but I was hoping you would join in.
While you are correct that the dosage provided by a CE (coffee establishment) is nobody's business; it is a factor when assessing value for money.
Last time I was in Adelaide I went to a Cibo in the city with clients, and ordered the coffees. I asked for double ristrettos, and also the mandatory latte and FW. I asked for them to be made with a double ristretto. I was charged an additional $1 per beverage for this. My seat afforded me a perfect view of the machine and barista in action. I reordered the same drinks, but omitted the request for the double ristretto base, and also just ordered another ristretto (not a double). I was served identical drinks, and my ristretto was the same volume as the first; even though the first was supposed to be a double.
Your discussion about dosage is spot on. Thank you for the input.
I have been served perfectly balanced and delicious espresso from a split shot, that was 30ml in volume. The CE knew its business.
Far too often I am served a ristretto when ordering an espresso and am lucky to receive more than a couple of teaspoons worth of beverage. I am sorry, but it is not worth $3.50 to $4, like some CE like to charge.
I won't mention the acidity problem, as that is just common place now. Too many "PURGER" fan boys in the "industry"
Apart from a very select few CE (and I do mean FEW), my wife will not drink espresso when we go out, though she will at home. When in Italy last year, she enjoyed perfectly balanced espressos every day, from many establishments in Rome. In fact at least two a day, especially if she was in the vicinity of one of the Illy specialty bars. No robusta was used in the Illy blend.
While many here in Oz, think that we know everything there is to know about coffee, and that the Italians are far behind us, and only use cheap beans; it makes me wonder how they can consistently serve well balanced and delicious espresso for between 1 to 1.5 euros. And yes they do split a shot.
Personally, I think that if I have to use 20g+ to make a shot of espresso, then there is something seriously wrong with my technique, or my beans (or my roasting).
However..... with some SO, and the odd blend, 21g does produce a very nice gloopy and viscous ristretto with enormous intensity of flavour.
As always there is no right or wrong way, just the pursuit for tasty coffee.