And daylight time is that plus one hour. They're both standardized somehow or other, that's not the point. The error bars on that relationship with the noonday sun are large enough that neither daylight time nor standard time actually fit that definition anyway. Time zones cover an hour-wide area, and orbital mechanics of the Earth and Sun cause noon to drift a lot throughout the year.

Both are workable, but one is more familiar, and that's daylight time.