And yet, as shown in my opening example above, two people with exactly the same amount of income pay vastly different amounts of tax. One pays four times as much as the other.
This is obviously fair?
Might be a case of "it depends"?
How did the private investor get the money to invest, from which their dividends result?
If it was from earned income which was taxed at the equivalent rate at time of receipt (as that of your first neighbour example), is it fair that already taxed money is taxed a second time?