Hey! Thanks for the comment!
> But why should a (public) library be interested in providing such services? For funding? What about costs?
Public institutions like libraries are usually funded through government mandates. We as citizens decided that having free access to books is a good thing and nations, states, and municipalities dedicate tax dollars to fund those programs. So, if we decided providing internet-based services through the library was also important, we'd enact mandates for that, too.
Not saying that's likely, but it is possible.
> At-cost service[s] provided by the libraries will probably collapse as soon as a for-profit company comes up with a cheaper plan.
At-cost actually means it couldn't be cheaper (at least if economies of scale are equal). That gets a little hairy because companies like Google can provide services like Photos and Drive for "free" because they make so much money selling search data, but generally speaking that's the deal.
> Also, host by a library still creates centralized service, which comes with all problems that a centralized service inherits. It only shifts the problem, not solving it.
Totally agreed – if there was only one library. But, there are tons! And as I mentioned, if the services are based on interoperable standards, you could easily move your data between services and have them talk to each other so there's no vendor lock-in. Think ActivityPub for files.
Thanks again for reading and engaging in the discussion!