All they had to do was standardize a rating system for bananas, and then countries could chose to ban whichever ratings they liked.
Its a clear system that allows and enables trade, while letting countries have their own regulation.
(But I don't understand what anyone in industry or government has got against the curative of fruit in the first place - what a pointless thing to classify by.)
You'd think that simple combinatorics would make people understand the benefits of this procedure, but unfortunately journalists always picked on the initial complexity of the rules. Especially during the 80s this was a "low hanging fruit" for writing another fun article.
In other words, pick any 28 random countries from the world and write an article that explains all of their import & export regulations, food safety standards, etc. You'll see what you get...
If the purpose was to facilitate trade, the way to do it is by providing information to those who want to trade, not by banning them from doing so.
Of course, you can always lament that certain countries blocked certain trades - acting on their national interests instead of the interests of the trade union as a whole.
What you cannot claim is that a system with bilateral treaties between 28 would in any way offer an advantage in terms of the complexity of the regulations. This claim is just nonsense. You can look almost anywhere you like and will find that the EU regulations have simplified trade tremendously over the years. Unfortunately, writing articles about how simpler trade among member states has become is less popular than writing another article about the ridiculous initial regulations which were derived from the existing trade regulations of the member countries.