Your flac size vs wav looks off to me. I just checked one untracked master (24/48) and flac is 465mb, wav is 723mb
The amount of compression depends on the dynamics/level of the WAV that is being compressed. If the WAV is normalized, without many quiet sections it won't compress as much as a WAV that has a lot of dynamics and or doesn't fully peak. For example, I just took a pretty quiet 24/48 master that is 2:15 long.
master WAV: 1.99 GB
master WAV amplified by 10 dB: 1.99 GB (same, as it should be)
FLAC of master WAV: 1.15 GB (ratio 0.576)
FLAC of 10 dB amplified version: 1.28 GB (ratio 0.645)
The amplified version doesn't compress as much.
As another example, in Adobe Audition I just created 20 min of white noise and normalized it to 0 dB
WAV: 201 MB
FLAC: 196 MB (ratio 0.973)
Because the WAV file was basically full (constant near peak) it barely compressed at all.
I would assume the other lossless compression CODECs work similarly.
PiedPiper's example is likely constant and loud with little dynamics.