In addition to what Michael said, there are a number of other barriers:
Compared to many global health interventions, AI is a more rapidly-changing field and many believe we have less time to have an impact, leading to a lot more updates-per-time about cost effectiveness, and making each estimate less useful. E.g. interventions like research on mechanistic interpretability can come into and out of fashion in a small number of years. Organizations focused on working with one political party might drop vastly in expected effectiveness after an election, etc. In contrast, GiveWell relies on studies that took longer to conduct than most of the AI safety field has existed (e.g. my understanding is Cisse et al 2016 took 8 years from start to publication; 8 years ago, about 2.5x longer than ChatGPT has existed in any form)
There is probably a much smaller base of small-to-mid-sized donors responsive to these estimates, making them less valuable
There are a large number of quite serious philosophical and empirical complexities associated with comparing GiveWell and longtermist-relevant charities, like your views about population ethics, total utilitarianism vs preference utilitarianism (vs others), the expected number of moral patients in the far future, acausal trade, etc.
[I work at Open Phil on AI safety and used to work at GiveWell, but my views are my own]
In addition to what Michael said, there are a number of other barriers:
Compared to many global health interventions, AI is a more rapidly-changing field and many believe we have less time to have an impact, leading to a lot more updates-per-time about cost effectiveness, and making each estimate less useful. E.g. interventions like research on mechanistic interpretability can come into and out of fashion in a small number of years. Organizations focused on working with one political party might drop vastly in expected effectiveness after an election, etc. In contrast, GiveWell relies on studies that took longer to conduct than most of the AI safety field has existed (e.g. my understanding is Cisse et al 2016 took 8 years from start to publication; 8 years ago, about 2.5x longer than ChatGPT has existed in any form)
There is probably a much smaller base of small-to-mid-sized donors responsive to these estimates, making them less valuable
There are a large number of quite serious philosophical and empirical complexities associated with comparing GiveWell and longtermist-relevant charities, like your views about population ethics, total utilitarianism vs preference utilitarianism (vs others), the expected number of moral patients in the far future, acausal trade, etc.
[I work at Open Phil on AI safety and used to work at GiveWell, but my views are my own]