Because, they are the same. Apple doesn’t recognize an Apple Music release to be any different than an iTunes release. They give the same iTunes ID if there is no difference in barcode, label, etc. There are some instances in which the barcode for MFiT is shared with Spotify/Deezer, etc. that are the same as Apple Music as well. Of course, I’m talking about only releases that share all the same information, not those with different barcodes, etc. Most MFiT would be unaffected as most get their own barcodes.