Are you under the impression people are buying land (land being rural land, not an acre in central London) in the UK for the sake of it? It's not priced in the same league as the USA, it's expensive, if it's not earning a return then it's not happening. So unless you're starting a some sort of windfarm or solar farm, it's generally going to be for farming.
Also, do you realise the opposition party in the UK, Labour e.g. the Guardian, are seriously contemplating pushing a LVT. So they aren't pushing these stories to punish their own. They're pushing these stories to justify what they'll do. And that adds to why would anyone buy any real chunk of land in the UK right now.
As an FYI - a quango is a nonsense lobbying group, it's not independent, anything they come out with can be considered nonsense. Doesn't matter who they work for, it's always doctored stats and the taxpayer getting rinsed.