"All new developments, be it homes, stores, or any other commercial building, increase traffic. "
Ahh.... kinda sorta. Since the context of your post is exclusively motor vehicle traffic, Iet's discuss trip generation from that standpoint. The California experience has found that well-designed transit-oriented mixed-use development can have very minimal impact on motor traffic in the area. A new 700 unit residential unit near my office, for example, has resulted in no net change to intersection level-of-service and no need to re-time traffic signals. The apartments are located directly across the street from a light rail station, and are within walking or biking distance to about 50,000 jobs.
Since development is inevitable due to population growth, we might as well put it near existing commercial and industrial areas. I don't know how urban planning works in Australia, but historically in the USA sprawling greenfield development is much easier due in large part to our environmental and land-use regulations.