I am by no means an expert, however to me this system appears to include: a globally agreed upon data format, a transmission protocol hardware distributed across the planet in ground stations and air vehicles, and 70 years of legacy.
And all of that is enshrined in legislation across many countries.
And while there is a modernisation effort in progress, the nature of this system means that things will move slowly.
In 2023 anyone can suggest a better data format and distribution system if they start from scratch. Good luck getting the world to use it and good luck getting anyone to care.