Best if you read this thread. There is a long list already, of the things they aren't doing and should be doing. For starters.
Maybe regulating rider behaviours could be a start, since the riders divebombing each other and sprinting on the crab seems to be a recurring problem.
Again: FIA could have more control of safety in F1 because the circuits are enclosed, and they own the land they are using, they can modify the circuits. Just look at the shape changes over time of long-time courses like Silverstone or Monza. Cycling not only makes less money than F1, but it uses public roads a far greater % of the time. They can't, say, instruct ASO to construct a 20m tarmac run-off at a hairpin on a mountain road or a sharp corner in an inner-city sprint run-in the way FIA can instruct circuit owners for F1. ASO can maybe get some kerbs dropped or a traffic island flattened to make things more passable, but for most organisers, just getting local councils to fill in potholes in the road is probably the sum of the influence they can have. Smaller races can't afford to shut down large metropoles or use major highways and thoroughfares, so they have to use smaller roads which are by definition going to be less busy and less well maintained. While the organisers may occasionally need to be brought to rights for taking too many risks with their choice of roads, the riders have to adjust their behaviours to the roads they face. You can't descend a mountain road in the Basque country, with its inconsistent goat tracks and sharp faces, in the same way as you would descend a mountain road in, say, Colorado, built with much more modern machinery with much better road surface, wider and better signposted. It's not because Basque race organisers are trying to injure riders, but because
that's what cycling in the Basque country entails. Cycling in Belgium has poor concrete and pavé road surfaces. Cycling in the Netherlands has road furniture everywhere. Cycling in Brétagne has repechos and tight corners on narrow farm tracks. Cycling in País Vasco has inconsistent, twisty mountain roads. That's just how it is, and I'm not going to be all that sympathetic if you're riding flat-out like you're on some sweeping bends on a highway with tarmac to make Bavarianrider swoon and then blaming race organisers for any accidents because you didn't know that they had twisty steep roads in the Basque country.
They can maybe put clearer rules on what is allowable in a sprint approach to try to minimise those stages with crazy amounts of road furniture, pinch points or sharp corners that increase the risk of crashes; they can maybe do more to enforce rules in the leadout and the sprint in order to punish those who ride recklessly - but the problem with that is that historically they've policed the outcome, not the offence, and the first time they policed the offence and relegated Peter Sagan in a TDF sprint stage contentiously, everybody yelled at them for ruining a good battle for the maillot vert.
But the Wout van Aert injury crash was caused on a perfectly flat, three-lane-wide piece of road. That's the kind of crash you simply can't avoid, because cycling is an outdoor sport. It is susceptible to weather - a bit of cross-wind can cause a touch of wheels or a loss of control temporarily that results in a crash. Marta Cavalli's terrible injuries a couple of years ago were caused because another rider had had a crash or mechanical and were riding head down as hard as they could to get back on to the bunch, and didn't react to another crash in front of them - both on a perfectly straight and innocuous piece of road. The Itzulia crash may have had worse effects because the organisers didn't put haybales or catch fencing on the outside of the corner... but it was the riders going too fast for the road that caused the crash to happen in the first place, and the way the riders had soft-pedalled the climb before charging headlong into the descent meant the péloton was far bigger than it would have been otherwise so more riders ended up becoming involved.
It's not that UCI or race organisers can't or shouldn't be held responsible, it's that they can - and should - only be held responsible for the outcomes they have any level of control over. Van Aert's and Cavalli's injuries are things that are entirely outside of organisers' responsibility. Things like Jakobsen's injuries or the Itzulia crash, we can blame the organisers for the outcomes of the crashes being worse than they should have been had the organisers done their job more responsibly, but we can't blame them for causing the crashes themselves, because Jakobsen didn't crash thanks to an unsafe finish, he crashed because of Dylan Groenewegen's unsafe riding - that was made worse by an unsafe finish.
Throughout this thread you've seemed to hang on to some idealised possibility where the riders can continue to throw themselves around with reckless abandon at 100% power at all times, taking every risk in the world, as the UCI and the race organisers will have the responsibility to guarantee their safety; but I'm afraid that's simply not possible. Cycling will never be made 'safe', only 'safer' - to think that real progress can be achieved with only one party taking action is naïve.
One problem is that the péloton used to self-police a lot more vocally and self-evidently. Riders who took too many risks in sprints and leadouts, like Graeme Brown or Romain Feillu, or who caused a particularly bad crash that ruined their reputation, like Roberto Ferrari or Theo Bos, had the bunch to answer to, and there were enforcer types in the bunch who would let the péloton's dissatisfaction with a rider be known, such as a Mark Renshaw. This self-policing meant the UCI didn't
need to get involved all that often unless somebody did something
so egregious it merited a standout punishment (such as Theo Bos literally wrestling Daryl Impey off his bike).