The whole FAA/EASA cert process is burdensome, but it is worth noting that the aviation industry has an impressive safety record. It is not at all comparable to the safety of a '55 chevy.
I think there can be little argument against the assertion that modernizing the general aviation fleet would improve safety. The majority of GA aircraft are using 60's technology carburetted reciprocating engines and running on leaded gasoline, and the cockpit is mostly analogue gauges with mechanical vacuum-driven gyros. Every car manufactured since the 90's uses fuel injection, yet GA pilots still need to worry about carburetor icing. That's not even going into other modern safety improvements like digital autopilot or ballistic recovery parachutes.