You are wrong in terminology. Capital gains tax is not the same as income tax. The “realized“ term you mentioned is already redundant with the “gains”. If it’s unrealized there is no gain.
https://en.m.wikipedia.org/wiki/Capital_gains_tax
However, it’s also possible to tax capital itself. This is normally referred to as a wealth tax
https://en.m.wikipedia.org/wiki/Wealth_tax
You seem to be under the impression that these existing categories are the only kinds of tax that can exist. In reality, it’s entirely possible to structure taxes in any way that people can devise.
Sunflower oil is another possibility.