Let's give Vernita some love, even if she doesn't need it. Unsympathetic view to a tragedy.
Oh, sure, there are the commissioned killings and bloodshed and what have you, but it's all strictly business. After all, employment options were--are-- rather limited for impoverished orphans from the proverbial ghetto, especially those of the female persuasion, whose other sole option for survival involves far less clothing and far more favors than Vernita feels comfortable with.
So, really, this whole DVA-Copperhead deal with Bill is essentially a career choice. A consolidation of disparate interests, if you will. When Vernita kills, it's with a sort of brute efficiency. It's got none of O-Ren's studied pageantry, none of Budd's almost-droll cruelty, none of Elle's gleeful sadism, and certainly none of Beatrix's preternatural grace.
Vernita goes along with El Paso, even though she thinks--knows-- that it's highly fucked up, because Bill says so without saying so and boss wins out over employee every time. Even if it's the star employee.
So Vernita drives down to this dusty little town on a hot August afternoon and lodges four bullets into Beatrix's body (not to mention some thirty-odd slugs into the rest of the congregation), and that's that. Only, it's not really that, because five days after El Paso, one day after Bill phones her saying (like so) that the Black Mamba has somehow kept her tenuous grasp onto this mortal coil, Vernita starts having nightmares for the first time in a long time. Wild, aching, sweat-inducing phantasms leading her to a simple reality:
Vernita is good.
Beatrix is beyond good.
And practical or no, Vernita will die.