It already is subject to taxes, massive taxes, in fact.
Capital gains tax, depending on your tax bracket, works out to paying the government about $9,000 if your property sells for $50,000 more than what you paid for it. That's a huge tax, and it's a tax the government loves.
If the government truly had our best interest in mind it would employ a reverse capital gains tax that gives buyers a portion of their losses back in cash. Say if you lose $50,000 on your home sale, the government gives you $9,000. That's only fair, right?
But capital gains tax isn't the end of a seller's costs. There are legal fees, transaction fees, realtor fees and other costs associated with that home sale. Now what about improvements to a home, what about modifications? Taxes were also paid for that home purchase (if new) and to the municipality in the form of property tax. When you factor in closing costs, selling costs and capital gains the actual profit isn't as big as one would think.