Final answer:
Barter is not a means of payment and is not as efficient as money on platforms like e-Bay, primarily because it requires a double coincidence of wants which is impractical in modern advanced economies. Money, on the other hand, is a flexible medium of exchange accepted by buyers and sellers, eliminating the need for mutually desired goods or services.
Step-by-step explanation:
Barter is not a means of payment when trading on e-Bay; it is not as efficient as money because barter requires a double coincidence of wants. In barter transactions, each participant must have something the other wants at the exact same time, which is highly improbable in complex modern economies. Money serves as a universally accepted medium of exchange, unit of account, and store of value. It simplifies transactions by eliminating the need for this double coincidence of wants. This makes money incredibly more efficient in facilitating trade compared to barter.
In contrast to barter, money does not require the two trading parties to have mutual wants. With money, buyers can purchase what they desire from any seller who accepts money, and sellers can accept money with confidence, knowing they can use it to purchase other goods or services they need. Thus, money's role in a modern economy is essential in supporting a vast array of transactions and a complex division of labor.
Considering the example given, if an accountant wants a pair of shoes, they need not find a shoemaker needing accounting services. Instead, they can simply pay with money, which the shoemaker can then use to buy whatever they themselves need or want.