A lot of issues come up when you tax land.

For instance, here in Texas, we have no state income tax, so most state and city revenue comes from property tax.  The property tax is relative to the assessed value of each property, and it can change every year (though the tax dollar amount increase on each individual property is limited to 10% per year).

For property owners, this can amount to a tax on unrealized capital gains, as the assessed value may rise far above what the property was purchased for.

Additionally, it creates a class divide among the population, with property owners shouldering a larger portion of the tax burden, even though everyone is allowed to vote on property tax increases.  So renters vote for new public services paid for by property taxes, but they don't pay the price of it immediately, unlike property owners.

There are workarounds for these defects, to be sure, but they are illustrative of some of the potential pitfalls.