It could be a combination of both a hardware and proprietary software in the different makers devices that do not allow cross-interoperability between the various makers’devices.
No one here works for Apple.
We are, largely, just Apple product customers/users here and many of us are NOT electrical designers/engineers OR have NO insight into ANY device makers’ electronics designs or schematics to be able to give you THAT detailed an answer.
Everyone here gave you their best answer possible to your question.
If you cannot accept these level of answers/replies, then there is nothing more any one here in these communities can do for you!
In addition, ALL personal, mobile device makers are competitors.
Do you really think that all of these device makers are just going to allow free, unobstructed device interconnectiviy between each other’s devices?
Hmmmm?