Can't speak for every case, but local concerts usually only made a bit of money when we were the ones hosting the show somewhere, inviting other bands, and selling tickets. Even then it was a bit of a gamble. More than a few lost us money.

Otherwise, if we weren't hosting, the money we were paid for playing wasn't even enough to cover band expenses (instrument maintenance, travel costs, etc). Selling merch helped. Selling LPs / EPs was usually just an attempt to make back the cost of recording them in the first place.

If the band was signed, things were different depending on their specific deal. But those bands probably don't count as just "local" anymore, at that point.