Well a brisk walk (from memory) is about 15 minutes a mile.
So people under the age of 10 and over 60 probably start having a non-negligible numbers of people who can't complete a mile in 15 mins.
And then you have an obesity + overweight rating of 57.6% in the USA according to Wikipedia (and this may not cover people who are not overweight but physically fit) and you can start seeing how maybe not everyone can do even a 15 minute mile walk.
For the record I know BMI is a bit of a weak metric for covering obesity given that anyone "swole" will have a very high BMI...
”Race Walking is a progression of steps so taken that the walker makes contact with the ground, so that no visible (to the human eye) loss of contact occurs. The advancing leg must be straightened (i.e. not bent at the knee) from the moment of first contact with the ground until the vertical upright position.”
and also states:
”All the Judges shall act in an individual capacity and their judgements shall be based on observations made by the human eye.”
Of note here is the “to the human eye” phrase. If one were to introduce electronic aids similar to those used in fencing to detect whether there always is a foot on the ground, speeds would decrease significantly.
I think running 5mph for 5 hours is a very ... achievable goal for the median person, but I don't think I would put money on the median person, or at least, American, completing that time without additional training from their current condition.
If you took a random sample of people -- or at least a random sample of people 18-50 with no outstanding health issues -- and put them on a "couch to marathon" 6 month training program, yeah, I think you could plausibly get a median finish of 5 hours (for comparison, the Boston marathon has a median finish time of a little under 4 hours).
I honestly wouldn't bet on the median person with no training getting off the couch and moving 26.2 miles in less than ~10 hours.
I don't really have much of an idea of what the median would be for time required to walk/run 26 miles. I doubt that there's any good data. The original comment just specified "men", which is presumably global and would include the elderly. I've read that about 45% of people are non-urban, which may be expected to increase fitness, perhaps.
> He ran behind a timing car driving 4:34 per mile
I think most men could pull 12 minute miles (26 in a row, that is), so maybe a factor of 3?