Land is cheap but building a house is expensive. If you want more supply then you are going to need to make building more economical.
There is also the consideration that "lifestyle" appreciation can also happen. If an area gets really built up, more things are happening in the neighborhood that make it a more appealing place to live in, the allure of that lifestyle will push people to buy homes that are probably not worth much in another location.
Land: 500,000
Improvement: 300,000
They tax that at $800,000Land can be very expensive. Especially when it has infrastructure built out to it already.