I've known that if one is performing in a 'public' venue, SOMEONE has to be paying royalties and it is usually the venue that pays to either BMI or ASCAP ... I know of at least one case where a musician was playing in a coffee house for tips and either BMI or ASCAP told the owner that a fee had to be paid or performers could only perform 'original' music ...
I've just never thought of the need to pay royalties if I post something on line for others to hear ...
I am a member of
APRA in Australia. And even when an artist/band plays original music that doesn't save the venue from paying fees. I played in an all original band
The Name for a few years and we got paid each year from fees collected by APRA even though our material hadn't been released by a record label. We would report the original songs we had played in venues over the year and the money came out of the fees they had paid. If they hadn't paid any fees then that would become a problem for them.