The article states "Any conceivable tax system discourages work, which is unfortunate but unavoidable." Henry George's "Single Tax," (typically applied as a land value tax) does not have this problem. It does not tax the "fruits of you labor" at all, it taxes economic rent.

It could easily replace both income and sales taxes, and  it already has a method of collection -- property taxes  are a superset of land value taxes, in that they consider both the value of the bare land (the land value tax), and the value of improvements on the land. Remove the tax on improvements and place the burden on the value of the bare land, and you encourage efficient land use without discouraging labor, *and* you make it easier to calculate (home value can vary widely within a single block, and you would have to figure land values for a property tax anyway)

In addition, it is *much* harder to avoid paying taxes -- it's not like you can live in your house "under the table." A 23-33 percent sales tax would have people trying to smuggle things in from Mexico or Canada (if the person were close to the border), or splitting the difference in price with an unscrupulous merchant.

Thank you Thorstein Veblen.

Marx held that land was owned by all the people, and that everything else was just accumulated labor. That's at least as useful as Henry George's theory that only land has value. Henry George's theory only works if you make unrealistic and unreasonable assumptions about fundamentals.

On a practical basis, determining a reliable value for land for taxation purposes is difficult because its value depends on its location and on several sets of improvements: those made on that parcel of land itself, those made on surrounding parcels, and those made to the general area like roads and municipal services, and utility availability.

The business of land development is an interesting concept and one that Henry George's theory can't begin to explain. A proper development project takes a relatively low-value piece of land and adds a properly-designed set of improvements. That makes it much more useful and thus much more valuable. The land is still in the same spot and it's still that same old dirt underneath but it's got roads and services and green spaces.

Your example of house prices varying widely within a single block is only true in an area without zoning and code enforcement. The older parts of Houston, Texas come to mind. A nice house in a bad area loses a lot of the value it would have in a better area. The worst house in a nice area is a good opportunity - you can add on to it or remodel it and increase its real value. Think of the possibilities!

Henry George didn't say that only land had value, he believed that society was the cause for the increase in value of unimproved land, and that this increase in value should be returned to society in the form of taxes.

And while it may be difficult to determine a reliable land value for taxation purposes, practically every community of reasonable size already does so, in the form of property taxes -- which are simply taxes on the bare land plus taxes on improvements -- and when they use eminent domain to take over a property for public use and pay fair market value. If anything, figuring out the value of bare land by itself would be easier, since you wouldn't have to consider improvements at all.

And for land development, it is possible to separate private improvements from publicly-financed improvements -- or even, when private improvements raise the value of surrounding property, to give a tax rebate based on the increase in collection from one's neighbors.

Finally, even if setting a fair value for unimproved land is difficult, the tax itself is far easier to collect and enforce than sales tax, particularly a sales tax high enough to encourage cheating or lobbying. 

For the current system of land taxation, it is only necessary to achieve a comparatively equitable value for a property. They use a system which collects sales data to develop price per square foot for houses and price per acre for land. If we were to rely on real estate taxes to finance government, a better level of reliability would be required. Finally, rents would go up significantly to account for the fact the tenants would not pay other taxes.