All of those places needed their backend systems to be up 24/7. The banks ran reports and cleared funds with nightly batches—hundreds of jobs a night for even small banking networks. The healthcare companies needed to receive claims and process patient updates (e.g. your provider’s EMR is updated if you die or have an emergency visit with another provider you authorized for records sharing—and no, this is not handled by SaaS EMRs in many cases) over night so that their systems were up to date when they next opened for business. The “regular” businesses closed for the night generated reports and frequently had IT staff doing migrations, or senior staff working on something at midnight due the next day (when the head of marketing is burning the midnight oil on that presentation, you don’t want to be the person explaining that she can’t do it because the file server hosting the assets is down all the time after hours).
And again, that’s the norm I’ve heard described from nearly everyone in software/IT that I know: most businesses expect (and are willing to pay for or at least insist on) 24/7 uptime for their computer systems. That seems true across the board: for big/small/open/closed-off-hours/international/single-timezone businesses alike.