I don't see the problem with time zones. All my devices and clocks (apart from the wristwatch) adjust automatically.

With one uniform time zone I would always have to look up respective business hours, whereas I roughly know the time in the main time zones.

What can be annoying is the constant time zone changes in the Southwest of the US, where the Navajo Nation observes DST, but the remaining Arizona does not and you end up changing the time even when driving shorter distances.