Well TMDB isn't a concert database. It's a film and TV database. For a concert to be added to the database, it needs to have a proper, official release. So when a specific artist's Coachella performance is recorded and released on DVD by a big studio "XXX at Coachella" or released as a special on a streaming platform, it can be added to the database. But concerts that only have fan recorded YouTube videos, bootleg DVDs, or were shown as part of a continuous live stream don't qualify for TMDB.

Using Glastonbury that happened last week as an example, if a concert is broadcast on BBC, shouldn't it be on the TV database?

For me, it is similar to something like Doctor Who where you can find all the seasons here https://www.themoviedb.org/tv/121-doctor-who/seasons?language=en-US but there are dozens of episodes that are lost media and are not available anywhere https://en.wikipedia.org/wiki/Doctor_Who_missing_episodes so should entries like this be deleted as well?

IMO those are all valid entries for a TV database and shouldn't be deleted

As far as I understand it, Glastonbury was a continuous live stream. So, no.

The festival was a continuous live stream, but concerts are stand alone.

For example: https://www.bbc.co.uk/iplayer/episode/m002fbpw/glastonbury-kneecap https://www.bbc.co.uk/iplayer/episode/m002fc1d/glastonbury-turnstile https://www.bbc.co.uk/iplayer/episode/m002fc56/glastonbury-parcels

My understanding is that if I wanted to create an entry for "Glastonbury 2025 - Friday Day 1" it would not be a valid entry, but "Glastonbury 2025 - Kneecap" should be ok.