Clocks used to be on local time. You typically had a town clock tower and noon was when the sun was overhead.
Then we invented trains. We introduced standard time zones so you figure out when the train would be at the station.
I'm not a fan of daylight savings time, but this proposed patchwork is throwing the baby out with the bathwater.
However, I'm fairly sure the growth of time zones will stop before people aren't able to reference day times with any certainty: ‘4 am’ still means ‘hella early’ worldwide (afaik).
Inevitably something goes wrong, delaying a train, and then it's dangerous because the timetable says it's clear ahead of you but it isn't.
Eventually the absolute block system was invented. You track where a train actually is, and don't allow more than one train to be in a "block" of track. But that took a whole bunch more technology and a whole lot more deaths to invent.
"In the UK, the Regulation of Railways Act 1889 introduced a series of requirements on matters such as the implementation of interlocked block signalling and other safety measures as a direct result of the Armagh rail disaster in that year."
In practice, if you keep in touch on a regular basis, you don't actually need to remember their time zone at all. You can remember the correct time to call in relation to your own schedule: "Got to call Grandma as soon as I get home from work. If I wait until after I eat dinner, she will be asleep."
In actual practice, that's how most people seem to handle long distance relationships where they keep in touch regularly. (Or maybe that's just me.)
Plus, it's the relatively rare Luddite that you can only contact by phone these days. A lot of people keep in touch with long distance relatives via email, Facebook or text messages, all of which allow you to send the message whenever you feel like it without worrying if the other party is currently available for live interaction. If you can contact them via such a method, you can arrange an appointment for a live discussion by asking them when they would be available for such.