I don't think you understand how the tzdata works: the tzdata folks only update the contents after the civil authority for a region changes the law.

So first you have to get all the law makers to update what the legal statues say and then you "just" update the computer systems. The latter is the 'easy' part, it's the former that's the coordination problem.

And as someone who was around for the 2005 DST change, I can say that may also be quite the coordination problem. (Though I think code has gotten much better since then.)