Correct! Most cables use copper due to its' low resistance, but it's too soft for the wear and tear associated with plugging and unplugging an appliance. Brass is an alloy of Copper and ZInc which gives it a low resistance but is harder than copper so is more suitable!
Brass is used because it has similar properties to copper, this prevents something called electrolytic corrosion, when two disimilar metals are placed together the weaker material over a period of time will degrade. Although Brass is more expensive to produce than say steel it has a much greater resistance to electrolytic corrosion and thats why nearly all electrical connections are made of brass and as CUPRA has said it is more harder wearing.