This is the second radiator in a number of years that seems to be disintegrating from the outside.
The thin cooling fins between the actual ribs are disintegrating, and turning into a copper-dust/powder.

Car is a daily driven 1973 Dodge Dart.

It's clear some kind of galvanic corrosion is happening here but I'm wondering why because it can't be an 'isolated issue'?

I try to save the radiator and apply a coat of satin black paint on it occassionally, but ofcourse this might slow it down but doesn't seem to stop it.