Yes, land value tax has been advocated by many, but has any country implemented this and made it their main (or at least a major) source of tax income? Why not?
There's an open question over whether anyone ever thought it would actually raise significant amounts of money, or if it was primarily intended as a tool to force a confrontation with the House of Lords. If the latter, it certainly did the job and helped establish the supremacy of the elected House of Commons over the unelected Lords.
In terms of revenue generation, though, it was much less successful - at the time it was abolished in 1920, the costs of surveying and valuing land had outweighed the amount of income generated so it was a net negative overall.
Taxing/reducing the land can be perceived as unfair to grandma. Having young struggling more than previous generation and getting much smaller spaces can also be perceived as unfair.
Depends on your side. Status quo is perceived as viscerally ugly to some.