In San Francisco, the annual library budget is ~$200,000,000. That's about $10/month for each San Francisco resident (including babies, elderly people etc.).

Some of the services end up being very expensive, like ebook lending. Some publishers basically charge libraries per loan ($X for an ebook that lasts Y loans), so while it is nice for residents it's not clear that it's a good value, or that it's a good use of tax money.

I once heard from a knowledgeable source that most of library lending is bodice rippers. These are available from Amazon/etc. pretty cheaply, which undercuts the value argument. And of course, there's practically no social value of providing the public with free bodice rippers...

I'd be interested to know more about the economics of lending DVDs and Blu-rays. Hopefully libraries get a better deal on these.

If everyone used the library as much as people say they are great, their shelves would be empty. Libraries have to be some of the most underutilized services.