When you are playing audio from a CD and there are read errors, you get a worse listening experience if you wait for the CD to spin around a couple more times trying to read the data again causing a pause in the audio than just playing the corrupted data block causing a short glitch in the audio. So that is what CD drives do for audio CDs. The entire format of an audio CD is different from a data CD, the audio tracks are not just files. At least early CD drives did the entire audio processing in the drive and they even used to have a separate audio cable that directly connected the CD drive to the sound card. All this means - or at least meant, I have not ripped CDs in ages - that you have to work pretty hard to get an bit accurate rip of an audio CD because a lot of the processing is done in the drive and the raw bit stream is not easily available to the operating system and applications. Especially error correction - which is best effort for audio CDs and does not guarantee the absence of errors - at least used to happen so early and transparently to the following processing steps that it was very hard to know what happened or did not happen to the data stream.