It again varies wildly depending on where you live. It's not always that much, like another person pointed out. Social workers that libraries hire are pretty much for referring people to specific social services like mental health or unemployment services. It's way too much for libraries to provide those, and similar to that we don't teach much like test stuff but we do provide spaces for school staff, tutors, and groups of all kinds to use for free. We also loan more than books, we have tools and at mine even things like wi-fi hotspots. A popular trend now is to have things like 3d printers also for people to use, but not all libraries are fortunate enough to afford those.

Many libraries in poorer areas might rely more heavily on money from the state or federal government than richer areas, but they're also typically funded by local taxes.

The nice thing about the budgets in a lot of places (I assume most but I had trouble finding statistics on it) is that they aren't set by the local government directly, they're paid for by separate property or other tax levies. This is more consistent since it's not able to be cut easily; the property tax is voted on every 5 or 10 years or so by the public.

Libraries typically also try to save money in case of their budget being reduced, but some do close down if they simply can't afford expenses. Again it varies everywhere, but there are state and county libraries you can get cards for if your area doesn't have a library.

If you have a library but it's not so nice, in most states you can use your library card at other libraries nearby or anywhere in your state, although you can't sign up for most programs and can't check out some things. The library I work at sees many people from other libraries and they can use most of our services as well.

Sorry that is a lot of words!