...didn't bother anyone until railroads entered the equation: astrology did take the difference into account, armies didn't move quickly enough to notice it: ju

...didn't bother anyone until railroads entered the equation: astrology did take the difference into account, armies didn't move quickly enough to notice it: just keep adjusting to local time every day or so (even on horseback, any tactic is far more dependent on physical limits, so you're coordinating on the order of minutes, not milliseconds). For railroads, even at 40 kph, an east-west train would be subject to time shift (not in the Lorentz sense, it would just keep switching "timezones" too quickly). Given that the primary security element was "this train is supposed to pass this set of switches between this and that time and wait there, else it risks colliding with that other train running opposite," both accurate timekeeping and geographically wider timezones were needed (as in "the railroad will use its own time, Prague's lunchtimes notwithstanding").