I've always assumed that this is because those who think land is just another free market commodity (it isn't) don't realise there's anything to talk about, so they keep quiet.
However, those that understand realise they can use land to bypass the free market and get a constant flow of free money through rent. They then routinely lie about it so they get to carry on.
My hope is that new technology such as the linked map of land ownership will lower the bar to learning how land works far enough that it becomes hard to lie about it effectively.
Land is a monopoly, but most people are not even aware that economists describe it as such, let alone knowing how the monopoly works. I think once that begins to change, we will see reform. More of an education issue than anything else.