Tax soil not toil means replacing taxes on production: labor, investment, and trade all together. With taxes on the value of land itself (while discounting the value of any improvements made to the land). Land isn’t the only limited resource/privilege Georgists can target for taxation (or other reforms) in lieu of taxing production and trade, but it is the biggest and most important as it relates to housing.

Unlike speculation in other commodities, land speculation (which leads to holding vacant land out of use) can’t be offset with any new production since land is finite, which leads to a whole slew of problems as parcels are wasted while raising the scarcity and price of usable land. When this is combined with taxing people on the work and investment they put into the land, much is lost.

Georgism seeking to tax soil and not toil would discourage people from holding vacant land out of use while not punishing (through taxation) landowners actually putting their land to use. This isn’t to say it’s the only solution to solving the crisis, but it provides a core benefit by giving the incentive to put land to productive use for the benefit of others instead of wasting it at the cost of others. There are real world examples of this too, New York did it in the 1920s to great success, many cities in Pennsylvania do a lightweight form of it by biasing their property tax towards land and away from buildings, and countries like Singapore have recaptured land values through a variety of means to fund widespread public housing.