> One clock may be an easily changeable thing, but is it really that much easier than changing one sign?
Mechanical clocks are imprecise and so need periodic adjustment. If you need good timing, then adjusting your clock periodically would be already baked in. Adjusting it differently would be essentially free.
Communicating that you've changed your schedule though, that's a lot more work. Phones are a new tech not everyone has. Telegrams and letters cost money and labor.
Plus there's an issue of synchronization. Imagine a whole bunch of people changing their schedules at different times. The barber changes schedule one day, the bakery the next, and the post office decides to wait until next Monday. It'd be pretty rough.
> But changing all the clocks, in a whole country (or on a whole continent), on the same day? You think that's easy? You've never got that wrong, or known anyone who got that wrong?
It's far easier and more reliable for a government to make a big announcement (radio, newspapers) and make a single, global change than for a lot of people to communicate with everyone else.
In modern times this is a lot more practical, but communication used to be a lot harder.