Land Value Tax (the Georgeism discussed in the article) just taxes the land on what it is worth, not the buildings on it. So holding land vacant costs more because the speculator is not making any money from it, while they could be making money from a building.
A side benefit for homeowners is that improvements increase equity and resale value without raising taxes
In CA there was/is a ban on SFH zoning. So at least in that case every homeowner should get taxed like at least a fourplex. Considering your wage didn’t increase that means less money for mortgage, etc., so buyers have less to spend on a house and your property goes down in value.
A side benefit for homeowners is that improvements increase equity and resale value without raising taxes