That's easily done with a writing pad with carbon paper between each sheet. You write the items, prices and tax, rip off one sheet to give to the customer and another sheet for the books. I checked, these seem to still be sold at office supply places, so there is no excuse.
Cash invoices will probably still work in most jurisdictions, to be recorded electronically after the fact. It's even more work than a handwritten receipt since the customer would have to be identified, not just what is being sold and for how much, so I wouldn't fault a merchant for taking out a service surcharge for it.
