Some horses have a natural jump and some love/like jumping. Those jumps you have pictures of are very probably young horses as the older they get the more they are going to realise that it is stupid and are going to back off..
Other horses don't like jumping as will not want to jump high..
They use young horses because they are too young and green to disagree.
Those people that jump the height of the wings and that height competiting don't get ridden at that height every single time they are worked.. the horses that jump the wing at home aren't the horses who jump the wing at a comp.
The Old video and picture is of a 14yr old point to point horse! Or so I was told. And milton- john whitakers amazing grey was well into his teens when he won his last big comps so I wouldnt say they are all young but I agree to some extent.
It made me think when you said the young horses do it through greeness and as they get older they start to back off....
My mare Flo now 5.5yrs (although she's not done alot of jumping due to her age) was very very keen when I took her jumping for the first time and would honestly jump anything you aimed her at. But now she is much more aware of needing a correct stride and more warey of certain colours and combinations. She'l never refuse but doesnt go at them like a bat out of hell with no breaks anymore! Hehe
But my friends 3yr old welshy has the same fearless attitude to poles and tiny cross poles as flo did at first! I wonder whether it will wear off, and if he will become more aware also?
I will see when tenny has his first go (hes too young at 3.5yrs to jump just yet but when he's 4 he can try his first cross pole) and ill see if he has a similar attitude.
Gotta agree that these animals jump because they want to. I've got a mule that will stand flat footed and jump a 5' fence. The only reason she stays in a pasture is because she wants to. When I was in Wa. We had 20 ac. Cross fenced and if she was at one end of the place all you had to do was call her she would jump every fence clear to the barn.
The heights these horses are jumping didn't happen over night, it takes years of training to get their agility, fitness and balance.
Are you asking these questions in concern, or are you asking so you can actually perform???????????
These horses have been trained over many years, by professional people....who have been doing it for years,
The best mare we had was only 14.2h, now that mare had wings, she could jump well over 5', and did it often without strain or injury, had a 16.3h that struggled to clear 3'. And had a 16h that cleared 5'6" without hesitation and was eager to do so.
It is not the height of the horse, it is thier "courage" and "willingness" to perform.
To explain that horses without human intervention, (apart from the fences), can leap on their own.
I have a 18 month old filly, at the age of 3-4 weeks, she cleared a 4' fence, "SHOCK HORROR", she is fine, (and may one day be a jumper)
You ask whether it is fair to jump these heights, I think the horses in the pictures tell the story, they seem eager to me.