So this is sort of clever in a why-didn't-I-think-of-that way.
Lo and behold, the problem seems to have been solved at last. There is now a clear plastic barrier over the code and then the silver scratchable coating sits on top of that so that you can either scrape it off – and unless you scrape hard enough to break through the plastic barrier you can't damage the code – or simply peel the whole thing back. Genius? Probably not, but it solves a common problem in an elegant way. I wish I would have thought of it, I bet that this is patented by someone!