Buzz: Sorry to offend you, but all these things are interlinked.
If the maintenance is done so consistently; and as mentioned by you; done by the EU and South Africa, then why were the V5 and other registered B737-200, belonging to the same company and being maintained there, not temporarily withdrawn as was done with all the ZS registered B737-200?
To operate into the USA on a schedule the departure point must be Category 1 classified.
Nearly the same rule applies to the EU.
SEE Nigeria, Swaziland, Angola etc.
Also have a look at the bilateral agreements and insurance requirements.
Ps. A DCA cannot be banned, but aircraft can be turned around.
The DCA is not loosing, it is everybody else whose license is not worth the paper…