It's not just a subscription thing, you can purchase individual shows ala bandcamp too.

But yeah, jam bands have really embraced this more than any other category of artist - it's quite common even among low-mid tier jam bands that every single show ends up on Nugs. These bands are often pretty friendly to recordists too (a recent show I was at has two recordings on the IA as well as the Nugs version. Everyone's happy!)

Phish gives people a code that lets them access the show they attend on livephish.com without a subscription. You can subscribe and get access to all of the shows. I think livephish.com is run by and/or shares the same platform as nugs.net but it's a different subscription.

Mike Doughty used to sell burned CDs of the show at the merch table (afterwards in case anyone was worried he was using some Is Chicago, Is Not Chicago technique to violate the space time continuum) back in the aughts.