IIRC, Cd's are wav files you are simply copying them.
CDs are 16-bit/44.1kHz PCM. Wave files can contain 16-bit/44.1kHz PCM data. But CDs have Reed-Solomon error correction, and wave files have a RIFF header. There is a process of extracting the data from a CD and packing it into a wave file, but it is pretty straight forward. Where as other formats require extensive processing.