I see what you're saying PCP, I just don't put much faith in the survey numbers.
I wouldn't put too much faith in the county numbers; the sample sizes are too small, and the study authors acknowledge that. They wouldn't ever estimate Talladega county because the sample size was too small.
But for the overall statewide harvest, they state a 9.4% standard error. They estimate a harvest of 45,301, so there is an extremely high % chance that the harvest was somewhere between 41,050 and 49,552. I'm not sure what their level of reliability is, but its close enough for identifying harvest trends and setting seasons and limits.
One flaw in the hunter survey is that it doesn't measure the kill by unlicensed hunters - those over 65 and under 16. And of course, it doesn't measure the illegal kill. If somebody killed more than 5, they likely threw away the survey.
But random sampling is used in every branch of science. I know of no reason to think this instrument isn't valid within the limits they state.