Time zones aren't just so everyone on the planet can start work at 09:00 local time. They're also for snapping everyone in a region to a shared time, even if it's a little off from their solar time.
Check out the history of railway time for the birth of time zones: https://en.wikipedia.org/wiki/Railway_time
For this one, It really amuses me on how they think they would accomplish keeping someone's phone to alarm at the equivalent of 7am when they fly across a nation.
Granted, I still hold the silly view that we should probably change daylight savings time to be a 10 minute change of the clock every month. Up for six months, down for 6 months. Would effectively be trying to tie it to actual solar time, which is what we seem to care about. And would be trivial with modern devices. (Though, no, I don't hold that this will happen.)