Not that long ago, and we keep fiddling with them. The US time zones were adopted just over a century ago. The dates for daylight saving time were changed less than 20 years ago. Much of Western Europe changed time zones (much of it rather violently) in the 1940s, as did China. The tz database often requires updates for changes.

If you want to go with what was settled long ago, that would probably be a return to each town observing its own time based on local solar noon, which would be pretty annoying.