Why does Toyota Share the Secrets of TPS?

During an overview of TPS given during a Just In Time training class, one of the participants asked why it was that Toyota was willing to share their secrets with their competitors. This is a question worth thinking deeply about.
Certainly Toyota has used TPS as part of their PR effort when starting factories outside of Japan, and this is reflected in the positive labor relations they have. For a time the Toyota Supplier Support Center was providing free consulting in TPS to Toyota suppliers. They were helping companies become Lean as a public service.
Toyota probably also knows that TPS is not as easy to copy as it might seem. It has been said many times that TPS is more than a set of tools, but it is very tempting to take the tools and begin hammering away at the Muda. You may be able to do this profitably for a very long time, but you will end up in a very different place than if you had adopted (and adapted) the whole Toyota philosophy.
The people at Toyota will tell you that TPS keeps changing. If you aim to implement TPS as it is today and you succeeded in 5 years, Toyota will have moved on. When Hiroshi Okuda became Chairman of Toyota, he said in his message to Toyota employees “I want everyone to change.” Even at Toyota where TPS has roots that go back more than 50 years deep, the plant (TPS) needs constant watering.
I heard a story that in the early days of Toyota Loom Works a blue print for an automatic loom was stolen. The people at Toyota Loom Works were calm, saying “We’re always finding and improving faults with our product so if the people who stole our designs build it according to that design, we will already be far ahead of them”. Perhaps Toyota shares their TPS blueprint with the world precisely so that they will never glow complacent, but will keep on improving to stay ahead of those who steal their designs.