Group With Different Helmet Intercom Brands

Hi!
My family and some of my friends have Fodsports FX8 Pro, a Bluetooth helmet intercom from Fodsports. It is a Chinese brand. So far, we are very satisfied with their sound quality and connection stability.
https://www.fodsports.com/fx8-pro-motorcycle-bluetooth-intercom/
Recently, my friends and I are planning to join with another group to ride together. Some of them have Fodsports M1-S Pro, others have Cardo, Sena intercoms.
We found that Cardo and Sena can be connected, but hard to achieve group communication. Sometimes can only support a 1-to-1 communication.
Maybe they use different tech? Why can't these brands come to an agreement and use the same technology?