No, it's up to the designer to build a file correctly. Unless you want to pay for the printer to "play designer" (modify the files). We've established this though, white background match #FFFFFF Nonsense. A printing house would be perfectly justified in bouncing the file back to the designer and stating it contains no white. If Naturarmed was to set up the file the way you recommended and send it to a printing house, there would be no white ink in the output, and any resulting cost would be upon Naturarmed (or his customer). Sorry, if I'd requested a white background and provided artwork that has a white background via a rectangle (illustrator by default looks like it's a white background but actually contains no background colour) and it came back with no white background i'd refuse to pay and the printers would know this, Infact i've sent 1000s with the above white rectangle and I've never been asked to do it any other way, plenty of printers used too. It most certainly does. White objects are commonly created all the time. White text in front of other colored objects is a most common example. But that just assumes a white paper. That doesn't magically cause an offset press to suddenly have an opaque ink in one of its printing heads. Print such a job on a brown bag, and your "white" will just be bag-brown. This has gone massively off point, I understand that a brown paper bag is brown and not white, one would not assume that but one would also know what they're printing on.
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