I have struggled to understand why houses don't get built and land sits idle for years. I can only assume that it's significantly more complicated. I'm not trying to excuse the complications. I guess if the house prices are forecast to go up, you build some houses, but not all that you can because the longer you wait, the higher the profit will be on the ones you start later. If house prices are going down, even if it's profitable when you start, you're not likely to build houses because you might be left holding houses that will sell at a lower margin. If there was a tax on unused land, that might skew things towards building more even if prices are declining, but I'm sure there are lots of views on that.