The Georgist movement (or Single-Tax movement) had a lot of momentum at the beginning of the 20th century. Major political leaders like Winston Churchill, Rutherford B. Hayes, and Sun Yat-Sen were all Georgists. There are various reasons for why the movement lost traction but I think it can mostly be attributed to:

(1) the automobile which increased the accessibility and productivity of formerly-marginal land, lessening the problem of equitable access to land, and

(2) the introduction of the income tax as an alternative to land value taxes. Notable, land monopolists preferred income taxes because as long as their land is unused or underused they are not producing as much income. The Georgist movement then split between those who thought that income tax was a good enough replacement and those who "knew" it wasn't.

There's also a kind of conspiracy theory which claims that (to a certain extent) neo-classical economics (which developed at about the same time that Georgism become popular) was promoted by wealthy and biased land owners and monopolists at the time with an intent to discredit Henry George and obfuscate the role of land in the economy, folding it under the definition of 'capital' to reduce the factors of production to just two, along with labor.