In areas that are arguably Europe, it looks like Iceland, Kaliningrad Oblast, and Belarus are the places that stick out.

I'm in California; most of Arizona is permanently in daylight savings, and we work with a lot of developers in China and India, which don't observe it. It certainly complicates things, sometimes.

I've done work on my product's logging subsystem before, and especially bugs with recorded times. Dealing with different DST rules is a mess.