It takes money, time, and discipline to do it right. The process needs a high perceived cost of failure to make it work. Can you imagine being able to sue Microsoft for damages of every Outlook exploit that one suffers? The current license absolves them of responsibility and there is no associated cost.

However, you may recall the NASA fast-track Mars mission fiasco where one sub-system used the metric system of measurements and another the English (actually just US and one third world country) measurement system. (If you read this, control yourself, Andrew!)