Well, I can only tell the story behind the 5011 set.
The ADAC is the German Automobile Club (like the AAA in the US). Many Germans are members as soon as they've got their driver's licence because getting help from their tow-away trucks or their vans (when you have a flat tire on the highway - that's why they're called the "yellow angels" - no kidding) will not cost you 1 penny when you're a member.
And now about the plane: For many years now there has been the option to upgrade your membership. When you have an accident abroad (and remember, when driving round Europe you're abroad very quickly) and you can't drive back, you'll be taken back on a plane to Germany to be treated or maybe operated here and not in a country where you don't speak the language (or where you don' trust the doctors
).
I don't know if the ADAC really OWNS such planes, but for children it's easier to understand that it's the ADAC that helps you instead of showing a plane or heli from another airline (which is probably what happens in real life).
So: the 5011 set basically shows all ways and means in which the ADAC will help its members.
That's why I think (especially with the AC in the logo - for Automobile Club?) that the mentioned set with the white vehicles is just the international version of the same story.
But that attempt at intepretation shouldn't keep anyone from making up more interesting stories
about these sets.
