Most taxes fall into:
Income you receive
Profit you realise
Spending you choose
Council tax sit outisde of this. Its more like levy based valuation bandings and was a quick and dirty fix after the poll tax fiasco. It is effectively a service charge not a wealth tax.
Whereas mansion tax is the government estimating the value your actual house, then treating this valuation as pure profit then taxing you on this. Given the majority of homes are purchased with mortgages and paid for by already taxed money:
Why is
Mansion Tax = Estmated value × %
More reasonable than
CGT = Profit * % (Profit = Actual sales price - (Purchase price + actutal costs)
With actual costs being renovations not stamp duty or interest paid on your mortgage
I am not in the mansion tax bracket. I do accept that some taxes need to rise but I don't believe this is the solution.