The big issue in my opinion is defining property/wealth (not just land and cars, but also intellectual property, art, etc), and then the feasibility of appraising all of that, and then litigating those appraisals (for the populace as a whole).
Seems like it could get into quite a bit of the country’s resources going to refereeing the game, which at some point takes away from productivity.
Though not really for the population as a whole: the majority of people don’t have all that much in the way assets. The proposals that get floated in the US don’t kick in until your wealth is in the tens of millions.
Capital gains taxes are income taxes. Property/wealth taxes are taxes paid based on the “market” price of an asset just for owning it (presumably society provides for its security and environment in which it became valuable and will continue to be valuable).