There are a couple of other reasons for stereo/mono differences.
1- Brian Wilson mixed The Beach Boys albums to mono because A- he is deaf in one ear, and B- he loved Phil Spector’s music, which was always produced in mono only.
2- Before the late 1960’s, when Rock ’n’ Roll finally became considered adult music, records were mixed to sound good on radios and jukeboxes. Many hours were spent on the mono mix, the stereo mix often left to an assistant engineer to do in a quicky session. Stereo LP’s were pressed only so the record companies could charge a dollar more per disc. When I started buying LP’s, the mono versions sold for $2.99, the stereo $3.99.
