Which is crazy, because it widely depends on the district.
You could be in rurals-ville, FlyoverState, USA and make a pittance. (Oh plus BTW, the excitement of torches and pitchforks coming for you, your staff, and your collection. Politicians also attempting to undermine the entire institution of libraries for strategic mob-outrage points. Ah, perks!)
Or in some urban areas that are well-funded, librarians and especially branch managers are paid stupidly well. Their jobs mostly being general management duties, listening to the complaints of the insane and unreasonable, tresspassing the insane and unreasonable, and answering "Do you work here? Where's the bathroom?" Of course, that's when they're not stuck in pointless meetings.
Lots of stress sometimes. But BMs make low six-figures. I imagine there's worse jobs.
But it's one of those things where a spot usually opens up only if someone moves, retires, or expires.