I was last in Sydney about 25 years ago. Apart from their “loop” it was a much more complicated system and I didn’t like it at all and it was confusing.

The only thing I liked about their train system was that it linked in with the airport which was a godsend at the time.

It was expensive and you had to choose a specific station to travel to as well from point to point.

Their colour zones seemed random to me and just unwieldy compared to Melbourne’s centralised 1,2,3 zone with the origin point being the CBD.

I’m not sure what it’s like now but I did not enjoy Sydney’s public transport system back then.