You make some good points.
If you watch the full replay with an open mind, you’ll see some nice rides and you’ll also gain an understanding of pentathlon riding. I recommend the two Lithuanian girls for this - they are light, balanced and forward. Perhaps not stylish eq riders but the rides are appropriate for the course on an unfamiliar horse. If you want to watch the men’s, the two from France are very experienced and ride in a good pentathlon style.
When I first got into pentathlon, I was horrified by the riding. Over time, I started to understand what the consistently good riders were doing right. They ride forward to the jumps, they stay balanced, they stay out of the horses way. If they have a problem, they fix it going forward - this is very important. They ride their lines clearly and meet most fences at the base. Again, they don’t look like they’re in the Maclay but they’re unfussy and efficient. They don’t try to micromanage. They ride the horse the way the horse likes to go.
The top people in the sport are the top people in the sport because they don’t leave much to chance. They know what to do to succeed.
When it comes to horse selection for pentathlon, you need to find horses that are resilient and don’t mind knocking a rail or two. In the US World Cups, the horses often come from eventing barns for this reason. This is why you school and test the horses over the course - you find the ones who can handle the elements of pentathlon riding. At Pan Ams in 2015, we had several upper level eventers like my pony and even a horse that had gone around Rolex. @Jealoushe’s mare was a solid Training level eventer. Etc. These were all horses whose owners said were capable of dealing with unfamiliar riders, a large crowd and jumping in multiple rounds.
A horse who expects things to be perfect all the time is not going to be suitable for a pentathlon competition. Organizers know this. Horse owners know this.