Exactly matching the sun day is not very important. It's more useful to have your time zones match your neighboring countries so that more people shared the same time.
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”
Exactly matching the sun day is not very important. It's more useful to have your time zones match your neighboring countries so that more people shared the same time.