Are Developers delaying projects?

SMH BusinessDay had a full page article about the number of projects in and around Sydney that are ready for building but have been waiting for years for the developers to start building homes. Land at Werrington has potential for 240 homes, but nothing has been done by the developers, Becton, since they bought the land three years ago. Why? Becton says it is because the state government didn't put a railway station in at UWA. Of course, if there was a railway station next door the homes would be enormously more attractive, but can that really justify the developer not building?
Becton also have a site in Waterloo, known as Sydneygate, approved in 2005 for 280 units, with 30% already sold off the plan, but apparently work has not yet started. Development consent will lapse in November.
Peter Icklow, CEO of Monarch Group, denies developers are sitting on vacant land waiting for prices to rise even further.
Tony Kelly, Minister for Planning, says "Land supply is there ... it exceeds the requirements for forecast population growth". Greenfield stock is at its highest level since 1981.
But Aaron Gadiel, CEO of the Urban Taskforce, says "the government figures are nonsense because they don't reflect where land is commercially developable".
The article specifically says that the upper north shore unit market is experiencing problems. All this seems to call into question the central tenet of the Hornsby Shire Housing Strategy - it's no good rezoning land for development if the developers don't want to build! Is there real evidence of demand for hundreds of small units in multi-storey blocks in places like Beecroft and Carlingford? If the demand isn't there then why would the developers build them?
It's worth remembering a quote from an article in 2009 - "Home builders and land developers do not have an incentive to increase the supply of housing and land to significantly above anticipated demand, as this would increase the likelihood of dwellings and lots being unoccupied, undeveloped, remaining unsold or falling in value, and therefore reducing profit."