Earlier quoted context omitted.
Why don't we have an additional distress beacon on all planes that says their gps coords to Inmarsat continuously no matter what? Basically why can't we use the Inmarsat network for more than distress but any and all planes report to some tamper proof system every minute? (Yes I know how many flights there are, but you don't need to store the data once a plane has reached its destination successfully)
It's complicated. One of the complications is requiring anything. Most trade agreements now in place defer major standards compliance in aviation to ICAO, and ICAO ends up being lowest common denominator when it comes to rules. Simply, less rich countries don't want to pay for every possible feature. Another complication is there's almost no such thing as a "backport" in aviation. The equipment a particular plane mod…
Aircraft have whats known as a Supplementary Type Certificate, which permits changes to a certified aircraft. Even a major upgrade from radial engine to turboprop has been authorized for some aircraft, including DC-3 transports made in the 1940s.
Another example is Southwest Airlines. The 737-300 series jets have glass cockpit upgrades for a common configuration between a 737-300 (Classic) and a newer 737-700 (NG).
If the ICAO mandates upgrades, it will happen. It might not be cheap, but its quite doable.