I am yet to see a system that uses namespaces 100% correctly, especially larger systems. XMPP is closest but they still have the stream tag defined as carrying

I am yet to see a system that uses namespaces 100% correctly, especially larger systems. XMPP is closest but they still have the stream tag defined as carrying a namespace, but as being the "same" stream tag without specifying it to be so, last I recall. The annoying thing is namespaces are not that complicated. They're probably five times more complicated than they need to be because you're always dealing with some library or system's half-assed bizarre implementation of them instead of the rather simple spec.