Did you read the article? It specifically says they will be ending that practice.

There will be no resale platform for CPH Half 2027. An entry belongs to the runner it is issued to and cannot be passed to anyone else

I understand that trail running "feels" different in terms of atmosphere and culture but I don't think the things you list make a practical difference for the purposes of this comparison.

I'd also argue that the goals of the runners aren't that different. There are two types of goals in both kinds of running: to finish and enjoy the journey, or to push yourself and see how hard you can do against an outside standard, whether that's other competitors or the clock. Sure, the proportion of who is chasing which category of goal is different between trail and road running, but I don't buy into the idea that the motivations in general are different.

Aside from the outcome, it's crazy that in 2001 there were still enough "Internet non-users" to make gathering data on them statistically significant

high impact

rock climbing

Usually these things are mutually incompatible

Yeah, I've run events up to 50 miles purely by feel (to include an ill-advised 50k in 97 degree heat and high humidity). As a middle or back of the pack runner, I think you're right. It's only if you get into the real competitive part of the roster that it would make a difference.

Why don't they just institute wave starts 15 minutes apart, first come, first served?

20km a week isn't nearly enough to finish a marathon safely. You'd likely want closer to 50km a week if you don't want it to be a suckfest. And why no walking? I think your advice is highly specific to a small sample size of runners