> I shouldn't need to adjust my wristwatch every few miles
> many clocks do not have line-of-sight to GPS satellites
> you can't put a GPS chip in a mechanical clock
> clocks on planes would literally run backwards
There is a reason most timezone offset by hours. It is very convinient for everyone to agree on the time when ignoring the most significant digits. Otherwise, you end up having meetings start at 17 past the hour, and be much harder to mentally calculate the offset.
You would also need to know the location of the other party much more presicily. At the moment, I know how to offset my schedule when planning a meeting with a customer in Texas.
This was done away with by the railroads because it made scheduling a complete nightmare.
The first use of "Standard Time" was by the Great Western Railway in the UK. Even in a relatively small country like the UK - only about 100 miles wide in most places - that was still enough to shift "local" noon by about 15 minutes.
Tomorrow morning, sunrise in Boston is 5:29; NYC 5:46; Dayton OH 6:29; Miami, FL 6:43, all EDT.