Most states have property taxes, so we do have forms of unrealized capital gainz.. especially since many states will update the value of your property from time to time based on their own assessments and then the amount of tax that you pay (many time annually) is based on such assessment.. which also is part of the reason that people will call themselves cashflow poor and capital rich.. but then they may end up having to start to get loans against their house just to keep paying taxes and of course their other living expenses that keep going up faster than their income (especially once they are on a fixed income).  Of course, we know that the robbery of the people is subtle with the ongoing debasement of the dollar (and other fiat) and the various other ways that property values are assessed, and assessments are made regarding how much of a cut (if any?) might need to go to either the federal government or state/local governments.