> Imagine an income tax not on what you currently earn, but on what you could earn given your schooling, credentials, experience, etc, and the available jobs within your region. Imagine how utterly unfair people would feel about that, and how quickly such a scheme would fall to widespread political pressure.

Yep, great analogy. LVT is the optimum tax from the point of view of maximising production incentives, but actually practical ways of extracting significant revenues from people tend to skew towards "this person/organization has liquid funds available and wants to do something enough to pay the tax on top". (For related reasons LVT-style approaches to taxation work rather well when the finite resource being taxed is something like broadcast spectrums which the average person doesn't own)

As for Single Taxing, convincing the public theres some ethical principle that PE funds buying tech stocks deserve to keep all of the rewards for risking their money on a particular venture and homeowners who lived through the area's dodgy-reputation years don't is a complete non-starter even though anyone with an economics degree can tell you why such an argument might be made...