As someone who managed public IT in a UK public library service until I retired (early) a couple of years ago, IMO the realities are very complex...
First question - what is your personal expectation of a public 'library,? What is that expectation of every central and local government body and agency to provide free support services fro them for which they pay nothing outside general taxation? Do these expectations match? 30+ years ago, the former editor of the Guardian, wrote an article quoting a Director of Social Services stating that a certain library was his biggest day care centre. Currently libraries are being touted as social centres to replace the disappearing pubs. All things to all people?
Since the mass introduction of Lottery funded public library IT around the Millennium, there has seldom been funding for regular refresh - it certainly doesn't keep up with market development.
If you close libraries, you generally lose the public IT within it - unless that is relocated, and that may not then be in a convenient place for users.
You will probably have queuing in peak times and lots of spare capacity at quiet times - if you only have one library open on a Sunday in an urban area, it will be saturated with demand for IT.
If you reduce library hours, you reduce access to the IT, unless you keep the libraries open (questionable term) in Self-Service libraries when the libraries are unstaffed, paid or volunteer.
How IT Savvy do you expect staff to be - with the hardware, software, online applications and services, whatever - alongside their other varied duties? Books (remember them?) management, user management, children's activities, etc.etc. Possibly loan tools and lawnmowers in future. How much do you pay them (if anything). How well do you train them? How well do you regard them?
The greater profusion of personal devices - even for those on low incomes - changed the demand on the service. Public WiFi - inside and outside the libraries changed the balance, and changed the game. Can you print from your personal device in your library?. Are library management looking at the metrics (if they have any) and pro-actively adjusting the services?
I could go on...
You get what you pay for, and as they say with politics, you get the leaders you deserve.