True. I was looking at TheKarateKid comment about infringing companies. The country where most stuff is manufactured, white labelled and sold at a premium by brand names :)
To understand some of the reasoning of what is open and isn't you can look at the different versions of their IPR, testing and use policies. There used to be 'profiles' but they were merged into one version: 3.0 IPR version 4 allowed anyone to use the specs and develop product 'based' on Zigbee and didn't protect anyone from IP enforcement from the many patent holders. This caused a lot of issues around 'interoperability' and end user adoption. "It says Zigbee but it doesn't work with other 'Zigbee' devices." IPR version 5 moved to improve interoperability and enable members to increase development by increasing protections. It granted RANDZ between all members. It improved interoperability by only allowing the use of the name and logo if the device was certified by an approved test house. This did increase deployments and reduced interop issues. Now there is IPR version 6, which allows for the growth of other protocols, providing the IP protection developers, manufacturers and retails want and could enable further industry consolidation - which is good for the end consumer. The average Joe and Jane just want stuff that works without having to be a technical expert. Any open source move is probably about getting more developers exposed and involved to help grow the base both creators - and consumers.
The UK, national smart meter effort. Sub gig, supported by three silicon providers did Zigbee sub-gig for the last mile, tough to penetrate homes and buildings. Running 3.0 on which means it will port very easily but sub-gig is much more regulated country by country than 2.4.
You can search. This article covers the initiative but doesn't call out the sub-gig detail:
https://telecoms.com/opinion/467631zigbee-and-the-smart-mete...