When I had a printing business, the profit was in origination – typesetting and artwork – rather than the actual printing. Phototypesetting and design were the printer’s domains, but desktop publishing and clip art brought an end to all that; customers brought their artwork with them and saved their money.
However, artwork that was print ready also removed the printer’s responsibility for accurate and error-free copy. I would always ask the customer if they had carefully checked their copy and the answer was always yes. But proof-reading is dull and it is easy to read what you want to read. The keyboard is a good clue as to where mistakes might be made. For example, the proximity of characters “y” and “t” sometimes made the intended “our valued Secretary” accidentally become “our valued Secretart”. (I’m sure this was always an error, but printing for amateur dramatic groups was always a tension filled area.)
Customer originated copy also produced text that might have been queried had I have typeset it. The political leaflet supporting the removal of visual, illuminated vehicle controls in favour of a gyratory system of road management was probably the most creative description I have ever read of replacing traffic lights with a roundabout.
Typos in printed copy have always caught my attention. The first draft of my will had to be returned for amendment. My wishes for cremation and my ashes to be scattered was printed as my “ahses” to be scattered, which is too avant-garde, even for me.