Sorry to split hair but until 1998 GiB didn't exist and GB were indeed 2³⁰ so it's wrong to say GB are now 10⁹ because of a decision of the BIPM from 1960.
GB are 10⁹ because in accordance with its mission the IEC made them so in 1998 which incidentally base its work on this 1960 decision.
Without the IEC, we would still have GB referring to 2^3,. I can tell as I lived through this change as the annoying cs student who correct something the professor said, in front of the class and is right about it.
When you say "GB were indeed 2³⁰", do you mean it was officially defined to be that, or that it was common practice for people to call it that. G- was officially defined in 1960 to be 10^9.
GB are 10⁹ because in accordance with its mission the IEC made them so in 1998 which incidentally base its work on this 1960 decision. Without the IEC, we would still have GB referring to 2^3,. I can tell as I lived through this change as the annoying cs student who correct something the professor said, in front of the class and is right about it.