Why aren't timezones strait lines?

the time zones 1 hr equal 15 degrees +- from 0 the greenwich meridian the date line +/- 12 180DEGREES zig zag s in the pacific around several island counties because they have adopted a day not strictly in line with their longitude for various historic reasons ,certain states adopted time to save daylight 1 hr more than it strictly should be.longitude doesnt lie its man who nudges the line