Since this is a discussion on philosophy in the context of knowledge and metaphysics, scientific organizations don't claim they provide proof (in the sense of logic and truth), rather they provide rigorous scientific evidence to support their claims, such as vaccines not causing autism. But science is always subject to future revision if more evidence warrants it. There is no truth in the 100% certainty sense or having reached some final stage of knowledge. The world can always turn out to be different than we think. This is certainly true in the messy and complex fields of biology and medicine.
Your claims are demonstrably false, there are many instances of authoritative organizations that explicitly and literally assert that vaccines do not cause autism.
Out of curiosity, can you realize I am arguing from a much more advantageous position, in that I only have to find one exception to your popular "scientific organizations don't claim" meme (which I (and also you) can directly query on Google, and find numerous instances from numerous organizations), whereas you would have had to undertaken a massive review of all communications (and many forms of phrasing) from these groups, something we both know you have not done?
A (portion of) the (I doubt intentional or malicious) behavior is described here:
I believe the flaw in scientists (and their fan base) behavior is mainly (but not entirely) a manifestation of a defect in our culture, which is encoded within our minds, which drives our behavior. Is this controversial from an abstract perspective?
It is possible to dig even deeper in our analysis here to make it even more inescapable (though not undeniable) what is going on here, with a simple series of binary questions ("Is it possible that...") that expand the context. I'd be surprised if you don't regularly utilize this form of thinking when it comes to debugging computers systems.
Heck, I'm not even saying this is necessarily bad policy, sometimes deceit is literally beneficial, and this seems like a prime scenario for it. If I was in power, I wouldn't be surprised if I too would take the easy way out, at least in the short term.
There's been some progress science must have missed out on then:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8207024/
That is one organization, many others claim they've also achieved the impossible.