That is only partially true. Very few games are well balanced to the point the house wins comfortably either way. I think sports fans would be shocked to look at the computer bottom line during games in progress. You can run simulations to see how the book fares based on this final score or that final score. The variance can be startling. Often there is some hidden parlay card out there that can completely change the outcome.
When that happens, you can guarantee there is rooting interest in that sportsbook, and not to a minor degree. I've witnessed tantrums galore in the back rooms. When Nick Bogdanovich was a young sportsbook manager at the Horseshoe he was so paranoid over every major outcome that he'd kick the filing cabinet in the sportsbook office when a game finished poorly for the house. We had patrons in the seating who would hear those kicks and laugh about it. They knew what it was. One guy would ask me to describe the latest dent, and if Nick said anything in the process.
This is how Las Vegas succeeds: the earn is almost always greater than the risk, even if a game is not well balanced. For example, you might win $63,000 if the underdog covers, or lose $44,000 if the favorite covers. So all year long you take that type of thing and rationalize that the results will balance out. Sportsbooks make an astonishingly low number of decisions. That's what struck me when I was hired to work as supervisor. It was basically hang the number and see what the bettors do with it.
In Sunday's game the Dolphins opened small favorite but the Buccaneers were pushed to small favorite. Somebody is going to have to explain to me how that aligns with a game fixed by Las Vegas. Apparently it was fixed to make sure the sportsbooks lost. They were anything but happy with that result.