The problem is sociobiological.
We have a genetically derived sense of justice that includes a sense of what constitutes "property', "theft", and "sharing". Our sense of right and wrong are shaped by what we have "learned", but is limited by a rather strong template derived through millions of years of natural selection.
Most of that template evolved before land ownership (or anything like it in a modern sense) was even possible. We understand that "wealth" (including but definitely not limited to land) is "property". We also understand that owning property carries with it certain rights, privileges, and obligations. Trying to exclude products of labor from taxation will inevitably lead to a sense of injustice in almost every citizen because it flies in the face of our innate sense of "natural law".
As satisfying and convenient as it may be to propose anarchy or a government funded exclusively through a tax on land, neither is sustainable because we all KNOW* that is "unfair".
We also "know" that there are collective rights that should be respected.
No matter how much or little land Bill Gates "owns", how "productive" he was in acquiring his wealth, or what he earns in annual "income"; 99.9% of the population will believe that he should be required to pay much more in taxes than the average citizen.
* Excepting of course the possibility of the occasional mutant or one whose education has allowed near perfect uncoupling of their consciousness from what the rest of us humans would call "feelings".