True, but Charles Shaw is also just $3.50 for 750ml. Even if I throw away half after 2 meals it is still cheaper than those $3 Sutter Homes.
About "cooking wines", or any cooking alcohol. The reason they have salt is likely for tax reason outside of US. Some countries tax their alcohol to discourage alcoholism, and if they salt the wine for cooking then they don't need to tax it.
1) It helps make the meat less gamey. You can also use ginger, chilli pepper, white pepper, etc, but it does break down some of the gamey meat's odor.
2) It help dissolve and evaporate the aromatic compound of food, and it does help tomato flavors and smells in blind test.
3) It helps emulsify oil in water, so it goes well with cheese and cream as well.