I never encountered them outside about a 500m radius of the zoo, but yes - they were very common in the zoo itself. In fact, I was surprised to find they were gone when I first visited the zoo after moving back to Perth about 7 years ago. I'm fairly certain they were still around in 2007.
The squirrels and the butterfly house being missing were the main things I remember from my first visit with the kids in 2017.
People always used to say that Perth never changes, but it really changed a great deal in those 10 years.
I's told the butterfly house got removed because the zookeepers found the butterflys were actually demonstrating really stressed behaviours when people walked through, but i don't know how true that is.
FAQ Perth Zoo
Perth Zoo’s Butterfly House was built as a temporary exhibit with limited funds and operated from 1995 to 2001. It stood where African Painted Dog exhibit now spreads.
Butterfly houses require a significant amount of energy to maintain the kind of temperatures, humidity and bio-security necessary to keep and breed butterflies from around the world in Western Australia. Suitable pupae (young caterpillars) also need to be imported into the State to display a good collection of butterfly species. This makes keeping and responsibly maintaining a butterfly collection quite a carbon unfriendly activity compared to other zoo activities.
The writer mentions Dasuri as filling the role of native cats. Had a look on wikipedia to work out what they meant, and i think they mean Quolls. I suppose they'd fill a cat-like roll. Interesting comparison though.