Neon doesn't have an ability that cancels out firing error/recoil or provides perfect aim with aim/triggerbot. She just goes fast as fuck.
They put that clip in the trailer to make her look cool, what else would they do, replace it with a clip of her just using the ability with no context, or her using the ability, completely missing, and then dying immediately? "Oh wow, so hype, I love realistic trailers, they get me so excited."
And besides, she can't shoot while running, only while sliding, even then it's wildly inaccurate. You aren't going to be able to just slide at an enemy and quadruple headshot them with a ghost. Maybe you'll get lucky, but 99 other times you'll just die. Maybe with a judge or a spectre it'd work more often, but even then the judge and spectre aren't exclusive to Neon, any agent can run and jump with those two guns and mow down their enemies. The issue isn't with Neon.