This is only partly true. They are designed for a closed system - ie to work with their own hub, and within this scope I understand they work well. They aren’t designed to be sold and included into other systems, although plenty of people do that, and therefore they aren’t fully compliant with the standards.
These blinds devices aren’t exactly cheap though - although it’s relative as compliant zigbee blinds are even more expensive, but these Chinese ones still cost around USD80 I think - so not exactly “cheap”. They also aren’t really “knock offs” - they are generally reasonable quality, and designed to do a job, and work within a system, and they do that well. However try to use them outside of their native environment is the problem…
I agree - it’s a real pain, but I can also understand why.
Last year I went through the process of certifying a device and it cost a lot of money, and took a lot of time. We had a device working well in the field for a few months with a couple of thousand users, but to get it certified we had to add a load of functionality that the system will never use and put it through a week or so of testing at an expensive test facility. The system was a smart meter system and to get the security certificates to connect to the meters we needed the certification, but it’s expensive and for closed systems, it doesn’t necessarily add value.
It will take some time, but I’m working on it and it’s not something you can probably help with. I’ve just received the Tuya hub and have sniffed the communications with this device so now know how to control it. The problem is that the binding needs some reasonably heavy refactoring to support custom code - it was written with standards in mind so that it could support any standards compliant device without having to add definitions or code like was required at the time the ZWave binding was written.
I have now done a lot of this refactoring, and once complete it should make it easier to add non-standard devices - at least to cover the application layer. If they don’t adhere to the lower level standards which are handled by the coordinator then that’s much more difficult (ie probably impossible) to resolve.