eh, what? The tax on $500K worth of stock or gold is zero. Also, home ownership is disincentivized by property taxes but also incentivized by the mortgage interest deduction, one of the largest non-corporate tax subsidies in America. And rental property is taxed very differently from property you live on.

I think it's better to say that land is sort of a one-off that is treated differently from every other asset than to try to compare it to other kinds of wealth.