That does not mean I think the shoulder belt or dual circuit braking or reverse lights requirements are bad laws, just that they don’t apply retroactively to machines certified or built before they were introduced.
This doesn't, shouldn't and has never applied to the aviation industry. As soon as anything is deemed unsafe or outdated, it needs to be changed.
"Has never applied"? This absolutely
does apply to the aviation industry. Today.
The airplane I fly was certificated under CAR-3, which was updated to Part 23 in 1965. My airplane was built in 1997 under a CAR-3 type certificate and the design did not need to be updated to any Part 23 rule changes. On transport jets, the same principle applies. 707s still flying need to meet the 707 type certificate, not any subsequent changes to certification (unless those are made mandatory by special FAR or airworthiness directive.) New 707s could still be built if there was economic demand for them.
Would you let yourself or your loved ones fly on a "no worries mate, she'll be right"-airline?
I don't let us fly on certain foreign carriers with a poor training record. I don't have any issue with any EU flag, Swiss, or CA/US/MX flag carrier and would readily let my family fly on any of those. I made an exception once on vacation for a day VMC flight on a carrier that I would not have been willing to use for a night or IMC flight.
Airline travel is almost incomprehensibly safe, even with the fact that airliners are not required to be continually changed and updated as certification rules evolve.
If they were made to be so, there would be pressure to not make incremental improvements to the certification rules (owing to the economic impact on airlines). It's not particularly different from evolving building codes or vehicle codes. We don't seize or make economically unviable people's old buildings or cars; we also don't do the same to airplanes.