The over/under is 37 wins, but if you bet the under a $100 bet pays $105. If you bet the over, you need to bet $125 to get $100. So even though the casino set X for the number, the pay out odds show that the casinos themselves are betting on the over.
There's a lot more complexities involved here, and part of that is because more people will bet against the Kings because we don't have a lot of fans right now so keeping the under low is protection. There's also a lot of Lakers money in Vegas (see how they opened at 4:1 favorites even before trading for AD and free agency opened) and Lakers fans are likely to bet against the Kings.