Thats an old saying designed to convince consumers in general that The American Dream was set up to serve them.
It has some basis, in that market driven economy will deliver what people are willing to buy, and if they don't they will go out of business or be bought out by competition who will deliever what the consumer wants.
Where it really falls apart, a terrible betrayal of the sentiment of customers being right, is where we THINK we are getting what we want, but are getting cancer instead.
EG - When the detergent is cleaning the clothes and leaving a nice scent, the customer got what he wanted, and the competing producers better keep up. However, no mention of the
Tri-Sodium-Nitrila-tri-acetate* in it, a known nasty kind of carcinogen.
Sorry if I complicated things a bit, but the truth about economic matters, and a corporation's products, is not as simple as customers having the power to determine the marketplace.
Regulatory bodies of our governments are heavily lobbied/interfered with by corporations, and actual regulation is therefore MORE influenced more by corporations than by consumers.