Even if they are making a 2-5% conversion on $10 affiliate sale for example, combine that with a CPM banner and you do the maths. Compare that with the parking page with the wrong image and no index coverage, you do the maths on maybe a 5-10% CTR at a parking page rate (who knows).
So to back up my original statement, does the basic website make more then the parking page we can make and educated guess been: Yes.
To take a quote from this post above "who knows"...not you, not me.
Do I believe Melbourne.com's park page has a CTR of 5%-10%, No.
Do I think you are making an informed guess. No.
Have you actually estimated estimated Sydney.com.au's revenue, No. (you'd like me to "do the maths")
Have I done the maths...no, Like I said I don't know its revenue and I don't think you have any idea either.
All I see is a site that doesn't look to be doing well, it has traffic and no business model, no obvious level of engagement from visitors. Some affiliate links and adsense...its junk.
So "back to your original statement",
for example they have been making money off this domain for years, imo far out weights a dodgy parking page with the wrong city image.
I don't think it far outweighs it, I think it is an example of unsuccessful development, it is as good as Hobart.com.au's success was, that doesn't mean the development adds any real value.