At least in the U.S., capital gains and dividends are reported on income taxes.
They are here too but at a lower rate. The theory behind it is sound as it is designed to encourage risk taking but like most of our tax codes it has been bastardized.
Those on the far left with a poor grasp of economics like to cherry pick the facts they use. Apparently the shareholders(owners) do not have a problem with executive pay or it wouldn't happen.
The real problem today is with the enormous pay and perks of government employees as we all have to pay for that wether we use their services or not.