It still requires manual labor. We used to have external usb drives per computer, with a script in udev that started rsync as soon as you plug in a usb drive with a certain id. So essentially, plug in a usb drive to take backups. Plug it out when it says it's done. But even that was too much to remember to do.

We've moved to doing nightly rsyncs. Laptops rtc_wake at 4am, but of course suspend again before the backup starts if they're not plugged in. Backups are done over the local network from the "home server" to a big encrypted btrfs usb drive (so we get snapshots). And keep the offsite copy freshly rotated by visiting my parents :)

But we still some times forget to plug in the laptop at night.