That’s a bit like saying “most large modern systems are written in C which was invented in 1972, therefore software engineering has not changed since the 70s/80s”. That machine is also probably not running a gcode flavour that would have made sense in the 70s anyways, with additions for active sensing, macros, etc.

Tools like UNISURF would probably not be able to handle the extreme level of detail on most of that model. The very long tool lengths you see in the video are much more complex than they look and require effort both from software and hardware to prevent chatter and breakage on titanium. The clearances in the video are also extremely tight in places, and while you could have guess-and-checked that in the 70s, it’s a very different workflow than the simulators that are basically standard use today.

CNC machining is a multi-billion dollar industry populated by smart people. While the fundamental technology of “spinning cutter driven by computer controlled motors” hasn’t changed in 50 years, the R&D departments aren’t asleep at the wheel.