UTC would make some things easier and some things harder. I think it would make reliably scheduling meetings easier.

Suppose you want to schedule a phone call for two weeks from now with your colleague in Melbourne. That's currently kind of challenging. It's fairly easy to accidentally agree to an inconsistent time. What if that two weeks straddles a DST change in one country, but not the other?

In UTC world, you agree to a single time, and there's no confusion. To pick an appropriate time, just look up the range of business hours in Melbohrne, and intersect those hours with the business hours wherever you are.

I don't really see how your google or clock app examples are compelling. Just google "business hours in Melbourne", and then save those in an app or wherever if you think you'll want that information again soon.