You are confusing property with land (not that I blame you; our language makes it confusing). Property is a term of legal art term that relates to the right to possession and control over something. There are many types of property, and land is just one of them. Artistic and creative works are another.
I'm well aware that there are many types of property. And property taxes don't apply only to land. But copyright and patents, at least, are more similar to real estate than any other kind.
