Do you encounter people using UTC regularly? While it's the closest we have to a world timezone, in my experience people don't use it much outside of a technical context.

I usually see Americans treat Eastern Time as a standard, with references to Pacific sometimes. In the EU, where I am, CET is the usual timezone used for specifying a time internationally. And regardless of the location, it's very common for people to specify a time in their local timezone first and leave it to the other party to figure out what the difference is.

I haven't encountered situations like someone saying "let's have a discussion at 16:00 UTC" to set up an EU-US meeting.