Don't wonder... because they are absolutely horrific. I've tested about a dozen of them against my Prometheus and the pocket scales averaged nearly 2 grains of drift across a 100rnd session. If you run them on their power supply from the wall outlet, its marginally better.I have to wonder how good they are, and with no back-up to check them against.
Bottom line is that most people simply are not asking very much of their scales, and as such their deficiencies are almost never discovered. As long as a shooter is able to cluster shots with some degree of regularity, they don't often spend any extra time looking to do better. It just doesn't take a very good scale to get to 1/2moa. It's because that is so easy to achieve these days, with the quality of custom rifles, their barrels, individual components, and optics being so unbelievably good... a guy can experience half a grain of drift across a session and it will just get lost in the white noise of that shooters performance.
Under more controlled situations with a reloading bench full of the best equipment available in the ecosystem, you can see which station is holding you back more clearly. As one operation gets upgraded, you discover others which could be improved. It wasn't until I developed the CPS that I realized my powder measure was a problem, and so it goes that way always.