When you work for money, the tax comes off the top. In most countries it is taken from your pay before you ever see it. You cannot wait, you cannot delay, you cannot dodge.
It is the most visible, most automatic tax there is, and it falls on the one thing almost everyone has: their labor. The harder you work for money, the cleaner the system takes its cut.
Now look at wealth that is owned, not earned. Shares, a company, property. In most places the growth is not taxed at all while you hold it.
The tax usually triggers only when you sell. So the simple move is to not sell. The gain compounds quietly, year after year, while the wage earner is taxed every single month.
If you never sell, how do you spend? You borrow. You take a loan against the asset, and a loan is not income, so a loan is not taxed. You live on borrowed money while the asset keeps growing behind it.
Then you die, and in many systems the gain resets for your heirs. The asset passes on, the spending happened, and the tax on all that growth was simply never paid. Buy. Borrow. Die.
We tell ourselves the wage is honest work and the asset is brave risk, so we tax the worker and praise the owner. The rate tells a colder story: the top rate on wages sits well above the rate on long-held gains.
Nobody drew this gap in one meeting. It was lobbied into shape over decades, one exception at a time, mostly by people standing on the lighter side of it. That is how a gap gets built without a designer.