If you look up the website www.imro.ie you will find out what this is all about. Irish Music Rights Organisation (imro) charges a blanket licence fee for the performances of copyrighted music used in live performances in Hotels or Pubs, and also on radio and TV stations. The monies go back into the music business and musicians/composers join up and get a few bob back. While it is impossible to track which songs are sung most and who deserves the biggest cut, they argue at least they are doing something to help the artists.
I don't know how much this licence is but this pub is obviously not willing to pay. Songs enter the Public Domain 70 years after their birth.