Whoa - that's totally false
There have been massive changes in eventing over the last 20 years that have made the sport and jumps remarkably safer.
That includes eliminating and changing many of the types of jumps that induce rotational falls, adding frangable pins to the jumps, veterinary checks, course design, etc.
In fact, the eventing community just met in here Lexington the beginning of June to further discuss safety and make more changes.
Do you know what one of the biggest problems is compared to 20-30 years ago? Relatively inexperienced riders. Riders that have not grown up riding ponies bareback at a gallop with a halter in a field, riding to hounds as children or teenagers, riding cross-county (hacking and jumping for fun) as a kid and young adult for years, learning how to fall, learning how to ride at speed over terrain over solid fences.
Riders today ride in rings.
And horses that are being bought up to upper levels without years of experience at solid fences and riding cross-country (same thing - foxhunting, bashing around for fun over ditches and hedge fences and through fields, etc) behind them.
Or, horses simply not really having the scope to be at a level (most injuries and falls are happening at LOWER levels)
Look at the biographies: look at the ages of the riders, look at the horses and their experiences - NOT what it was 20-30 years ago.
The best eventers used to take years - years - to bring a horse up to Olympic capability. They would talk of a promising horse "maybe" being ready 6-8 years from now. And they would NOT put them there if they were indeed limited as to being a lower level horse.
Now anyone with enough money buys a horse, and a trainer, and goes for it.
The sport is trying to get more qualifications written into the rules (regarding advancing through levels) so people cannot readily put themselves and their horses at risk, but of course those very people are fighting it.
There's really alot going on, and has been. It's quite unfair and untrue to say, "nobody's doing anything to change that".