I would assume that, in a large city, those counts are routinely wrong and mismatches are ignored. If I try to count even a few dozen items twice in a row, I’d be lucky to get the same count twice. I can’t imagine poll counts are better.
As an election judge, I'm not sure how different Baltimore is from Philly, but we are not permitted to physically leave the polls if the count (voters_entered - votes_cast = 0) is off by one at the end of the day. There is not slop in the daily counts. A chief election judge could just close out the tallies and lie up the chain, but if there was an audit, they would get caught. (ps - they got caught)
The other scheme was advising voters inside the polling place (illegal) and signing in non-present voters and casting votes on their behalf (also illegal), so the counts would all look legit. They got caught for that too, it sounds like.
