[wongarsu]

A wide variety of decades-old aircraft, and even newer aircraft are often modernized versions of ancient aircraft models. All of them built and operated with the motto "if it ain't broke, don't fix it", because every change brings risk (and costs money).

There was also a lot of resistance to the idea that every aircraft should broadcast its position, heading, etc. because of privacy concerns. And as long as there are holdouts the tower can't rely on the information being available