Zwave is just as “standard” as Zigbee, and probably more so, since every zwave device has to go through certification by the zwave alliance in order to use the name of the protocol. That is not true for Zigbee.
Both standards allow for “manufacturer proprietary” message profiles, but zwave still requires that the device respond to “basic” ( that has a specific meaning in a zwave context) commands, while Zigbee does not.
So any certified zwave device can be added to any certified zwave hub and will at least respond to on and off, which is not true for Zigbee. This is the “interoperable” part of the zwave standard.
.
However, there is a regional aspect to zwave which you may be thinking of. Zwave has different radio frequencies in different regions, in order to avoid interference with local first responder and mobile phone communications. Zigbee offers a global frequency which is the same everywhere.
https://products.z-wavealliance.org/
Back to those dual logo products
The ADT/SmartThings dual logo sensors use neither zwave nor Zigbee and operate on a frequency different from both, requiring a special radio which is not available in any other SmartThings hub. Or any other ADT panel. It was a joint product of both companies. There was one exception: the leak sensor, which was just rebadged, so that one can be used with a regular ST hub.
BTW, many security companies use a proprietary communications protocol in part to discourage hacking. That’s not unusual in this market niche.