It's definitely not. Illegal drugs are also much more expensive in Australia than in many other places in the world. There is a growing problem with black market untaxed "chop chop" tobacco here. The tax increases have made it more and more attractive to both importers and smokers.
If you smoke the same amount of weed, it's probably not cheaper, but since it's typical to smoke maybe one joint per day but 20+ cigarettes, yeah, weed could be cheaper.
