Unfortunately if you’re Dell and you try to do this you actually have to pay for every song they play. But first you have to know what song they are playing.
The obnoxious part is where companies like Apple who actually choose and license nice music play it in such a way it sounds absolutely horrible on the phone. What a waste!
The frequency passband on old-school analogue POTS isn't wide enough to play music with acceptable fidelity. The upper frequency limit for POTS services is 3.4KHz, which is far below the ~15Khz needed for half-passable music fidelity.
Modern digital is worse because it combines the frequency passband of analogue with combinations of codecs and bit rates that can't support the audio complexity of music.
It's a challenge to make music sound nice on the phone. From Apple, I'd expect they'd try to get their hold music setup for 'HD Voice' which would help, but just stuffing it into POTS is going to be pretty icky.
Surely if Apple though it was worthwhile, it'd be pretty simple for them to remotely fire up iTunes and play your iTunes Favourites playlist at full iTunes streaming quality through the phone app while on-hold with them. (And for the lulz, make it play every song you've ever skipped when you're on hold with Google. Which'd be one of those wait-10-years-before-anyone-finds-it type of easter eggs, 'cause that's approximately the time between real people finding an actual working support number for Google... ;-) )
The obnoxious part is where companies like Apple who actually choose and license nice music play it in such a way it sounds absolutely horrible on the phone. What a waste!