You don't even need the graphs, miles driven per year is a sum. Sums converge to gaussians yet here the deviation was half of mean which means they used a uniform variable generator for miles.
What am I missing? The mean of a normal distribution can be any value. A normal with mean 2 and deviation 1 has deviation equal to half of the mean.
Is this related to the fact that miles driven can't be negative (unlike a sample from a genuine normal)?
Was M = 26,098.4, SD = 12,253.4 enough to infer a uniform distribution?
No unfortunately it is not. It's perfectly plausible to have a normal distribution with mean = 26k and sd = 12k. Although those numbers do look kinda weird, but nothing you could verify. I am not sure what the F(*) means here, maybe an F statistic? But that seems wrong if you are comparing two normally distributed samples, you might expect a T statistic.
To verify the distribution you would need a histogram or you could get fancy with a qqplot. You could also try a statistical test for a normal distribution but these fail on large sample sizes so the visual plots are your best bet.