Looking at the ACE website, they recommend 3 and examined 100 organizations. The cost-effectiveness estimates for the top charities seem to be heavily based on the same studies (with related methodological issues) suggesting that veg*n ads/flyers have incredibly high persuasion rates. The analysis of media impressions also uses those same studies to estimate how much meat reduction media coverage will give. There is also some discussion of policy changes and legal activity, as well as RCTs, but they place less of a role in the cost-effectiveness estimates.
So it looks like the reason the estimates are so high is because of the claims that 2% of people reached with ads/flyers will give up meat, combined with selection of organizations whose activities are evaluated in terms of ads, flyers and videos. I would worry about regression on the studies more than on the selection of charities conditional on the studies being right.
Looking at the ACE website, they recommend 3 and examined 100 organizations. The cost-effectiveness estimates for the top charities seem to be heavily based on the same studies (with related methodological issues) suggesting that veg*n ads/flyers have incredibly high persuasion rates. The analysis of media impressions also uses those same studies to estimate how much meat reduction media coverage will give. There is also some discussion of policy changes and legal activity, as well as RCTs, but they place less of a role in the cost-effectiveness estimates.
So it looks like the reason the estimates are so high is because of the claims that 2% of people reached with ads/flyers will give up meat, combined with selection of organizations whose activities are evaluated in terms of ads, flyers and videos. I would worry about regression on the studies more than on the selection of charities conditional on the studies being right.