I don't buy books much, but it's definitely an issue with electronic tools. Scales, calculators, heart rate and oxygen monitors, computer accessories, or really anything with cheap electronics that aren't _too_ complex and sells well is counterfeited. If you can find the components on tindie, then they can likely find them mass-produced and cheaper, and if it sells well and makes sense to have someone design a copy and manufacture it then they're going to. Whether it ends up on Amazon specifically is a different question. Typically it's a matter of when and how long, not if.

Obviously this becomes an issue with tools because unless it's an exact copy being made in the same factory (which does happen with outsourced Chinese products and this is typically when you'll see /almost/ exactly the same product with 10 different listings and 10 different brand logos on them), it doesn't have the R&D and QA that the original product has. Even if they are made in the same factory, they don't necessarily have the same quality, latest software, or warranty of the original. Where the American company that outsourced that oxygen meter may have opted for the medical grade, consumer-safe plastic and tests each batch, the counterfeiters are happy to use the cheapest materials they can find, which are at best only lower-quality, and not actively unsafe. Counterfeiters make money through active deception, and money is the goal, so they will _never_ pay for the best materials and tech. If they can source the metal made with lead for 5% cheaper than the non-leaded equivalent, it's not even a question. They are going for the cheaper option, because that's 5% more profit.