The musicians union was acting on behalf of the artists. For a long time, it worked. It led to the formation of the Grand Ole Opry, the Louisiana Hayride, the WLS Barn Dance, and many other radio shows that featured live performances.
No, they were working on behalf of union musicians in every city who would play thier rendition of hit songs and standards, not whoever recorded it first.
The Opry and raw KWKH show and a variety of “big signal” station live shows originated well before the musician union got its great strength and power over radio, which was after the mid-thirties.
The musicians union is a signatory to this act. If the AMFA were to pass, musicians would get a 1% royalty. That's what they currently receive from digital airplay.
Before the later 40’s, the hits were the songs, not the artists. Every band played the current favorites, and in towns like Knoxville and Topeka and Youngstown, local bands played on the radio. In fact, much of the reason for man, many stations to originally be locate in hotels was to have easy access to the bands that played in the hotel’s ballroom.
Today, we have, usually, one singe version of a song. other than tours by the artist who made the hit, there is little in the way of covers played live the radio.
All the early legislation was intended to protect those local, live performance musicians, not the band on any of the often many recorded versions of the same song.
Part of the problem is that the royalty would be based on revenues and not profits. The recording industry is familiar with procedures in which expenses always exceed revenues. That's a game they've played with their artists for years.
But now the bulk of recorded material is owned by just a couple of labels. In the past, there wer hundreds of labels and in many cases they did not own the rights to the songs… complicated by most songs having many recorded versions on different labels.