Payouts from records were also quite meager unless you were already a well-known act.

Music labels contracts have always been exploitative, they usually require the band to pay back costs like studio time, producer, mix/master engineers, marketing, before getting their cut of royalties in sales, for artists without clout the royalties share would be 75/25 to the label (or worse), more famous acts can get a 50/50 split, again after recouping the costs.

As any passion industry it is extremely exploitative, as much as people like to hate on streaming platforms nowadays the music labels have been the most evil aspect of it all for 70+ years and they managed to lurk in the shadows without attracting a lot of flak.

Sometimes the band would get pennies from an album sold in stores, but they'd get almost the entire price of an album sold by them at a venue.

Authors would get something similar, they'd rarely sell out their advance, but could buy copies for pennies on the dollar and sell them at conventions.

Getting paid for live performance was the traditional way for musicians to earn money for centuries. Record sales was a temporary thing that is now gone.

Sadly that wasn’t true in the past either for the majority of acts. The labels made money from both parts back then.