It's only the really small amounts that are by volume. Most kitchen scales don't weigh accurately enough to do a teaspoon or a tablespoon. Everything else is in grams these days. Unless you're using a pre-decimal cookbook, in which case it'll still be pounds and ounces.
What you'll never see in a British or European recipe is cups, because that's completely retarded. How big is your cup? How densely is it packed? Just put that fucker on the scale and weigh it.
A cup is 8 fluid ounces, a volumetric measurement. Ounces also is a system of weight, so people sometimes confuse the two. Ideally, fluid ounce should be written as
fl oz and ounce as
oz. However, this is often not done and you have to do some inference as to which makes sense.
When it comes to baking, it's advised to not use cups precisely because the amount can be significantly skewed depending on how packed the flour is, as you noted. The big exception is water. 1g = 1mL = 1 cc, 1 fl oz = 1 oz. Lots of times you'll see recipes call for 1 cup of water and 3 cups flour. 1 cup of flour is generally regarded as 120 grams and such recipes are better expressed using ratios, by weight.
My go-to pizza dough recipe is 2:3 water to flour, 1/15 of flour in olive oil or butter, 1/40 flour in salt, 1/50 flour in instant yeast. If using 3 cups flour (360 grams), this equals to 360g flour, 240g water, 24g oil, 9g salt, 7.2 g instant yeast. This will yield enough for 1 half-sheet pan pizza/2 calzones or strombolis/2 medium 14" pizzas/2 large 16" flat crust pizzas. I use a bread machine, so I weigh the water, tare, add salt, tare, add oil. Weight the flour and put that on top. Weight the yeast using a postal scale and sprinkle that on top of the flour. Put bread machine on dough setting, then let it knead and rise. Extra dough goes in the freezer to be used later or you can punch the dough down and do a second rise in the fridge.
