Why doesn't Melbourne commision art in more public spaces, roadways, bridges, etc?

It was really the first thing I noticed when I was in QLD years ago; no blank concrete walls along the freeway, but lots of commissioned art.

With the Westgate tunnel on the later stages, there's already a lot of blank concrete walls turning covered in graffiti vandalism.

So why is Melbourne, a city renowned for the Arts, not doing what would then a lot of misappropriated and vandalised spaces into art prices?