16 Problems Nobody Wants To Admit About Captain America: Civil War
4. The Scope Of The Event Is Impossible To Recapture
On paper, Civil War wasn't all that long. The main run was a mere seven issues and a lot of events were crammed into a short time, which was a positive thing for critics of the series, since there's a fairly strong suggestion that the arc isn't really all that good in the first place.
But the issue for a film version is that most of the best parts of Civil War happened in the tie-in threads that happened in other comics (like Black Panther and Punisher notably) and in the aftermath of the war itself. That's not to mention the build-up, which was great in the comics and has been horribly under-cooked in the films (to the extent that it should have been a Phase all to itself).
The long and short of it is that Marvel are having to compromise on the event. That's why it's a Captain America film. They're stripping away elements to cherry-pick a more compact story out of it, ignoring the fact that the scale of the event was hugely important to its success. But then, since they're unlikely to explore about 80% of the aftermath anyway, that probably doesn't even matter.