No - east-west Australia stretches further than eastern Ireland to western Ukraine. And that’s an opinion, not a fact. Time zones are just a way of estimating when people in a location will be around and having a way to communicate who you’re using as a reference. You’re free to use UTC today, if you want to - but it’s not generally useful if you also have to manually map out “x is in England so he would be at lunch 2 hours earlier than me, but y is in Belarus so after my 4pm he will be leaving work for the day”