For its part, Amazon contends that it cares about books and that low prices are necessary to keep people reading. However, the critics don't buy it. They insist that Amazon is only trying to protect its lead, and that the lower prices are strictly incidental. The industry groups certainly have a vested interest in this complaint -- the publishers' pricing deal with Apple was meant to get Amazon raising prices, after all. However, there's no question that Amazon wields a disproportionately large amount of power. It accounts for more than a third of all paper book sales, and it's responsible for up to 85 percent of some publishers' sales outside of libraries. Some writers and sellers have little choice but to accept Amazon's terms if they want to make a living, and that's bound to create some regulatory concerns.