I think that's definitely part of it. It's very interesting to observe the lifecycle of many of these services. - The company has a business need. - Because of

I think that's definitely part of it. It's very interesting to observe the lifecycle of many of these services. - The company has a business need. - Because of the economics of scale, it often makes sense to develop an internal solution. This is true both for fullfilment centres, and for purely internal problems: e.g. a video conferencing system for half a million employees. - As the product matures, the team or leadership recognises how people beyond Amazon might benefit from it. (think fullfilment, AWS, etc) - The internal service becomes a public product.