To these women, I strongly recommend this site: The Metric Kitchen -- it includes a rather detailed table of cup/gram equivalents for non-liquid ingredients. 1 cup of flour = 120 g, 1 cup of white sugar = 200 g, 1 cup of butter = 240 g.
Also, note that in the US, a "stick" of butter is completely standardized: 1 stick = 1/2 cup = 8 Tablespoons = 1/4 pound = 240 grams.
But I agree that the "portions" on American food containers are ridiculous, and almost always too small for a normal adult. (Obviously, they use small portion sizes to make the food seem lower in fat and calories. But sometimes, foods that are naturally low in fat/calories will use unrealistically large portions to make the amount of fiber, proteins, and vitamins seem higher.)