Taxing capital gains on properties is fraught with difficulty, particularly when properties are owned by offshore entities, and even the Land Registry do not know the identity of beneficial owners.

Taxes on property transfers (capital gains, stamp duty, etc.) also create hysteresis in the market, which should be discouraged.

It's much easier to implement a council tax style system, with non-payment a criminal offence, and the ultimate (if extreme) threat of property confiscation quite practical to go through with.