Well, in order to win that beautiful bag of lemons, you needed to not only think of the answer, you actually had to write it in the comment section ;)
To be honest, I'm not sure there is a true answer, or at least the one I'm about to give seems debatable.
The common answer is that guys are generally bigger than women, and because (body)weight moves weight, it is easier (generally speaking) for men to generate force on a rower. The same rule here applies to the assault bike, ski erg or any other similar piece of equipment where the output is a function of force production.
For running, unless you make a case that it is easier for taller people to run (not sure about this) and guys tend to be taller, the distances should be the same. Weighing more does not give you an advantage when running.
To simplify this in a practical manner, there are weight classes in all weightlifting sports, rowing, but not running. Does that make sense?
The fascinating question within all of this, which I actually believe is the main driver in determining these prescribed differences (more than bodyweights) is the idea that guys are naturally stronger than women.
Is that the case? It certainly seems that way, but if you're a guy reading this, how many girls out-lifted you in 18.2a (quiet Connor)? Did they lift more than you because you are stronger? But if you trained more you would be stronger. Are you sure? Is it that easy of a question to answer?
I'm definitely not taking a stand either way here, it is just a curious and fun theory (some would say fact) to challenge and ponder.
20 minute AMRAP of: [teams of 3] 12/9 reps of assault bike 8 reps of burpee 4 reps of clean and jerk at 115/80lb