I love going to concerts and I tried pitching this to producers, bands, etc. They just don't care unfortunately.
My mindset was: They already did most of the work, just exporting the audio (that already exists!) would give them extra income. Could be a subscription service, or pay per album, or even for free (it's a marketing channel).
Some bands don't want their live recording out there (multiple reasons: from errors during the live show, or to keep the experience exclusive, or they think some people won't want to go to see them live if they already can listen to it). There is also the aspect of "If we release it for free or in the platform, we can't never make an actual live recording album", which could make some sense.
For years I dreamt about this "Netflix for unreleased live concerts" platform but I couldn't reach anything. Maybe I am really bad seller, and I just needed help from someone with more experience with the industry.
I ended up doing this unofficially for my faovurite artist, with the help of friends and collectors, uploading bootlegs (sometimes amateur recordings, sometimes board sound recording), and catalogued so you can search for all the plays of a particular song, or an album, how many times this song was played, if there was a guest, filter by country, city, year, etc, etc.
I think it's a little more nuanced than "bands/producers don't care" and a bit more complex than "exporting the audio (that already exists!)".
Directly exporting the audio straight from the mixer would not necessarily produce quality recordings because the audio there is tuned for the purposes of sound reinforcement. To properly record a live concert requires an entirely separate setup with their own microphones and then some direct output from the mixer on a per channel basis to allow for post-production editing.
And a lot of people don't care about that! Lots of people are happy with the quality you'd get straight from a cell phone microphone.
But the people on stage and the people in the industry ... they're the ones actually involved in producing the sound, and many care very deeply about the quality that gets recorded and then shared. That's not to say that all musicians are like that, but many are!
There is also the legitimate view that a concert is a physical, ephemeral experience shared by the people in the room on the night. That is it fleeting is part of its beauty, in the same manner as live theater.
Which is not to say no concert should ever be recorded, but I could understand why it wouldn’t be a priority for some artists.