There has been so much more safety education in the last 30 years. It's bound to have rubbed off a bit.
we're talking about the technology and quality of the cars across time as it relates to safety.
you pull in people as drivers and it fundamentally changes what we're talking about. more examples:
"I think it's unfair to compare cars from 50 years ago against cars today without comparing the state of modern traffic laws and speed limits"
"I think it's unfair to compare cars from 50 years ago against cars today without comparing the quality and ubiquity of roads, highways and interstates"
etc.
http://www.roadandtravel.com/safetyandsecurity/highwayfatali...
Note that nationwide statistics are not available that far back, but consider this report from Washington State:
http://www.wsdot.wa.gov/planning/wtp/datalibrary/Safety/MVFa...
It can also be attributed to better education, more cracking down on drunk drivers, etc.
see what i did there? ;)