[nitrogen]

Anyone buying music in FLAC is deluding themselves if they think they can hear a difference between that and a properly encoded lossy codec like MP3

Because of inadequacies of the MP3 encoding format, no bitrate of MP3, even the max, can encode all possible things that the human ear can distinguish. There is one song I know of with a particular synthesized effect in the upper treble that is very profoundly different from the lossless original even in a VBR0 or 320kbit MP3.

Additionally, I've read that MP3 (I don't know about AAC) doesn't preserve enough phase information for effective use with matrix-encoded (e.g. Dolby Pro Logic) surround sound audio.

But Apple's engineering resources are not infinite, and it would be a flagrant waste of those resources to spend them on issues like this that impact effectively zero Apple users.

What was wasteful was inventing ALAC instead of using FLAC.