In my experience most people, including most developers but perhaps excluding many HN readers, don't understand what the timezone setting does. The time on all contemporary computers is always Unix Epoch Time, which is close to (but not exactly) UTC. Setting your timezone doesn't actually change anything about how time works on the computer. It just changes how time is printed. That's it.
So the second problem is that our text-based server world, for all its benefits, doesn't cope well with per-user parameters. I mean ... timezone support on Unix is basically buggy. It doesn't matter what TZ I set in my .profile, nevertheless the timezone of logs is in whatever TZ the server is running in. That's pretty stupid. And even simple calculations like "how many seconds elapsed between this log entry and this one" - which is really common - are very difficult, regardless of the TZ setting.
In my own personal perfect world, all logs would be printed in the first column of log files using the epoch time in seconds, and we'd have a command which would convert from the epoch time to the local timezone. So we could do something like:
tail -f /var/log/messages | grep 'panic' | timestamp
So for me, this whole argument over UTC is dumb. It doesn't matter what timezone the system is set to; any zone can be "default". The real problem is that different users have different time formatting requirements, and to date we haven't had tools which deal with that properly.
(even logging all timestamps consistently in ISO format would be a big step up...)