My first thought here is that an open market for translations would just create lots of really bad, free translations and make discovering good translations impossible.
Ultimately, there will be a concern that it devalues the translation process, leading to translators getting paid less, not more.
I'm not aware of the landscape right now, but for a long time the absolute best translations were free, and potentially baked into pirated videos.
Anime viewers tend to be passionate, I think there's a reasonable chance to have groups emerge with a reputation to defend and getting paid more than they are now (which could be 0)
> I think there's a reasonable chance to have groups emerge with a reputation to defend
This already exists today -- translation groups rush to be the first to translate a new series, and some fans have strong preferences around which groups provide the best translations (both in terms of accuracy and style). You can see the set of groups doing translations on the AniDB page for any Anime you like.
I remember watching a video a decade ago, of someone doing review of the subs for each group that was doing Black Rock Shooter, specifically the wheelchair scene, because what it's said has to be taken within the context of what's presented.
This could work in the same way fiction podcasts do: Have an editorial board rank decide which translations they want to pay for.
Make sure the editorial board is paid a living wage and the translators are too. Set up a marketplace for a dozen such organizations, and let them compete. All the incentives align.
It's already happening. There are visual novel groups that take pateron sponsorship to run the script through machine translation. It's now done in giant batches. They're released for free and I am not able to speak of the quality as I've never tried them, but when I see reviews on steam for a VN that has been machine translated, it never results in a good review.
this is a huge problem with opensubtitles - download count or year count for a TV show or movie's subtitles tells you absolutely nothing about how reliable it is.
Ultimately, there will be a concern that it devalues the translation process, leading to translators getting paid less, not more.