Wealth and income are different, but flows (I.e. increase) in wealth are absolutely economically equivalent. Try spotting the difference when both end up in the same bank account: you can’t
An increase in wealth is not economically equivalent to an increase in income. For by definition income is a receipt. A change in wealth may be a receipt – if you cash in – but it could be simply a change in valuation. And thus something that doesn’t arrive in a bank account because it has not been cashed in.
And, amazingly, we do have a tax system which taxes increases in wealth which have been cashed in. What we do not have is what The Tuberousness is suggesting, one which taxes wealth not cashed in, that economically different thing.