The central aspect of "Lean Thinking" is the identification and fulfilment of customer added value, because in the end it is always the customer who decides how good a process is. Because it is the recipients or buyers of your goods, services and information who can really judge to what extent you deliver the right thing in the right quality, at the right time and in the right form. Therefore, you should constantly question and optimize the fulfillment of these requirements.
Therefore, Taiichi Ohno deduces from the question "What is the customer willing to pay for" that there is too much waste in the value creation process that does not provide the customer with added value. Therefore, his goal was to optimize the entire process between placing the order and receiving the money.