My possibly biased perception is that people in Europe are more "internationally aware" (for lack of a better word) than those in the US. e.g. a website that is built in Europe but likely to attract international interest will include a timezone.
The schedule[0] for this just has dates and times. I have no idea when anything is, though some of it looks interesting.
Is there a "default" timezone that Americans assume on an American-centric site that doesn't actually state timezones? California?