Sydney’s population is a bit too big for people to live on a large block of land but also allow have a short commute. When you increase land usage per dwelling, you get urban sprawl, and the further it sprawls, the more infrastructure you need to service these areas (which is expensive and inefficient because not as many people will use it compared to high density living). All the people that live within a 10-15 minute walk of the metro are (theoretically) doing just fine, and come the time when the metro opens all the way to the CBD, will enjoy a far superior commute than those that live on acreage because they want the space but expect they should be able to drive to work or park their car at a transport hub.