When I was a child my parents had a purely mechanical scale, with a dial to adjust the zero.
Yet another case of why fix what isn't broken. Only, I expect that an IC or two and an lcd to run a digital scale are cheaper at volume than some amount of mechanical clockwork, once the cost of batteries is pushed off on to the consumer.
A quick glance at Amazon seems to confirm your intuition. The cheapest mechanical scale I can find is $32 but there are lots of electronic ones for ~$15.
Yet another case of why fix what isn't broken. Only, I expect that an IC or two and an lcd to run a digital scale are cheaper at volume than some amount of mechanical clockwork, once the cost of batteries is pushed off on to the consumer.