i don't know if i'd call it a design error but it is a cheaper design to manufacture than the more expensive kind that requires calibration. could also be a patent workaround. for something like 10 bucks many years ago i got some nice stainless 12" ones that work fine other than the lower battery life thing. they do lose track if the battery is low though and you move the jaws quickly. just have to have a bunch of batteries on hand and/or take the battery out when not in use.
What's really annoying is that they could have sidestepped the whole problem by simply putting a simple physical on/off switch on them, instead of the soft on/off button they use. No one uses these cheapo calipers for more than a few minutes at a time anyway, so the battery would probably last a lifetime with a normal switch and no one would notice that it's a power hog.
> simply putting a simple physical on/off switch on them, instead of the soft on/off button they use.
that's true but a physical switch needs to be placed and soldered while the soft on/off just needs to be placed atop it on the traces on the pcb. cost just probably was the biggest issue.
