I work with quite a few people who "need" to print things every day.
First of all, the vast majority of things they print don't require printing in the first place. As an almost stereotypical example, we have one lady who:
* Prints out every PO (that she creates in our ERP system) and puts it in filing cabinet #1.
* When she gets a packing slip, she manually matches them up, staples them together, moves them to cabinet #2, then records the PO as received in the ERP.
* Then when the invoice comes... Ditto, cabinet 3 (if she receives it by email, she actually prints that so she can physically staple them together).
* When she sends payment to the vendor... cabinet 4.
* Finally, when the payment clears, she stamps it as processed and files it away forever in the dungeon, "just in case" she needs to reference it sometime in 2046.
I've tried explaining that she can run a recon right in the ERP for every single phase of that, including attaching emails/PDFs/whatever directly to the workflow, but she doesn't "trust" the computer (aka "once upon a time I screwed up and deleted something, so I'll just do the whole damned thing by hand until the end of time").
Second, also related to trusting computers - I've shown people how to print to PDF. Nope, computer might crash (mind you, we have reliable offsite backups going back to the frickin' 1980s).
Finally, people seem to have a disconnect between the idea of computer files vs paper files. How could they ever find that one invoice among thousands of PDFs? Because y'know, you can't just organize them exactly the same way you do paper files, never mind the fact that you can just search for any bit of text in the document and almost instantly find every reference to WidgetCo going back to the beginning of time.
The paperless office will eventually exist. It just won't arrive until the Boomers and their hatred of trees finally gets the hell out of the workforce.