Well, for starters they can if they have to and if you pay them to, but maybe not in the military. I assure you that a well run practice isn't missing things like this - at least not for very long.
Secondly, one the purposes of having a coder is to perform audits of charts, op reports, etc. to ensure that they're being properly coded and to intervene when they are not. that simply doesn't happen in the military. All of the coders I've worked with wouldn't know a mistake if they saw it. It may be from a technical problem, but that is why you have an actual person checking the work at some point. It doesn't have to be every chart. If you had 753 miscoded encounters, that would have been caught with a basic, percentage audit.
The problem is that while coders are considered very important in the civilian world (because they can mean the difference between a successful practice with a reasonable workload and crushing failure), they're just not seen as very important to the Army. At least not when RVU production isn't a hot button issue that month. Even when it is, the problem is always assumed to lie with the physician or provider - "why aren't YOU seeing more patients??" The truth is, since we directly associate physician workload with RVU production, a coder isn't just a coder in the military, they're the same as a coder PLUS an insurance negotiator (because, of course, in the real world what matters is how much money you generate per RVU).
The other issue is, of course, that even if they caught it what would the military do to fix the problem? The answer, of course, is nothing. Other than maybe make it your problem somehow.
I look at it like this:
You know how to doctor. I know how to doctor. I will always do the best job that I can and I will always code my encounters to the best of my ability, not because I love the Army but because its the right thing to do. I'm not an expert coder. i would love to know more, but it's a full time job, as evidenced by all the people who do that as a full time job.
After a chart leaves my hands whether or not anyone believe I actually did any work or not is entirely up to resources out of my control. I'd prefer that they hire someone competent to control that process, and that would be an experienced, certified coder (at least). Someone who can at the very least identified if there is a system problem causing a mismatch. Someone who can correct my coding if need be. Because otherwise it'll always be someone in the command suite who doesn't understand the process themselves asking me why I'm not doing more.