Why did economist John Kenneth Galbraith believe that Americans postwar economy was a new phenomenon?

John Kenneth Galbraith believed that the postwar American economy represented a new phenomenon due to its shift from traditional market dynamics to what he termed "countervailing power." He argued that large corporations and government played significant roles in shaping economic outcomes, leading to an era of abundance and consumerism. This marked a departure from pre-war economic principles, emphasizing the influence of technology, advertising, and collective bargaining in driving growth and consumption. Consequently, Galbraith viewed the postwar economy as characterized by a unique interplay of institutional and social factors that fundamentally reshaped American life.