If this was so successful why is not implemented in other fields, such as education.
There are attempts being made to introduce ideas similar to those of lean manufacturing to the educational realm today. However, just-in-time production (JIT) is not really possible in education and even lean manufacturing is much more suited to the mass production of tangible goods, not to the production of services.
JIT production cannot be adapted to education. JIT is meant to reduce inventory costs by receiving raw materials just before they are processed and sending them out as soon as they are finished. There is no real way to do this in education because the process of educating students does not involve inventories of raw materials.
Lean manufacturing would be at least somewhat more possible in education. It would theoretically be possible to remove all the steps from the process that do not add any value or which add less value than is optimal. The problem with this is that it is very hard to determine when value is being added in the educational process. At which exact point is a student learning? Is it important to stop providing art classes because they do not add value or are they in some way important? These are not questions that can be answered objectively and so it is very hard to do lean manufacturing in the field of education.