Yeah, ATMs closing during the evenings and holidays! This kind of things has pissed me off more than once, but it's getting slightly better nowadays.
The office situation is pretty much like you described, and faxes are still very much in use everywhere. Stuck in the 70s.
I renewed a mortgage recently. I was told: you don't have to come in to sign anything. Just print the PDF's that we will send you, scan them, sign and e-mail them back.
That is basically faxing --- only significantly less convenient.
More likely is that it's to save money - if there is a cost incurred in supplying money for other banks or keeping the machine filled with cash, perhaps reducing hours is simply a cost saving measure.