You're right, i think most stories about the vietnam war were written by americans.
Yep, and there are great historians of World War II from Germany, Japan, and Italy; plenty of great sources and histories of WWII written by Jews; plenty of sources proving the Armenian genocide, and Turkish oppression of the Kurds, and Americans writing about horrible shit America has done as well as great shit America has done, and Russian writing about horrible shit Russia / the Soviet Union has done, etc. Shit, Southern historians' complete bullshit argument that the antebellum South was some beautiful place tragically taken away was the standard narrative throughout most of America for decades after they were crushed in combat.
You make your career as a historian by showing that the way people have understood something is wrong or incomplete, or were asking the wrong questions in some way or another, not by supporting nationalist sentiment or applauding the status quo. Maybe in Soviet Russia the 'victors wrote the history,' but not in the free world, not for centuries.
Now, what academic historians accept / know isn't always reflected in grade-school curriculum, because state-level boards (and sometimes individual teachers) choose the lesson plans at that level, so there's plenty of shitty history taught at different levels there. Over time the state-of-the-art eventually trickles down, though. There are probably a few teachers teaching the 'War of Northern Aggression' still, but that myth was WAY more common just 1-2 generations ago. There are very few college-level history classes taught that are very far outside the cutting edge, though, if only because the shrinking of the academic job market has meant that even smaller schools are getting historians trained at elite universities these days.