Music and singing should be treated the same as darts, quizzes, etc, but to my mind there are three (not two) levels of activity to be addressed.

1. An exhibition darts match, designed to attract an audience, probably with paid performers, and probably advertised both in the pub and in local media.

2. A darts league match, which is planned in advance and "advertised"
by a fixture list on the pub notice board (i.e. not at all "spontaneous"). Spectators are not expected, but nor are they banned or even discouraged.

3. A few friends meeting in a pub and deciding on the spur of the moment to have a quick game of darts.

I think both we and the council officers would agree that type 1 is regulated and type 3 is not. However, the officers appear to claim that type 2 occurences are "regulated entertainment" for music but not for pub games.

A regular, planned session with low-key "in-house" advertising can be no more and no less "regulated entertainment" than a league match of darts, dominoes or quiz.