That said, your assertion is not true. 15% is higher than the effective tax rate of 10.5% paid by the average single teacher in the US:
Average salary: $60477 [0]
Standard Deduction for single filers: $12400.
10% bracket for $0 through $9,875 == $988 tax. 12% bracket for $9876 through $40125 == $3630 tax. 22% bracket for $40126 through ($60477 - $12400 - $40125) == $1749 tax.
This totals $6367, which is 10.5% of $60477. Less than 15%.
The numbers are different if the teacher is married, has children, interest, etc.
We can discuss whether it's fair. I said above, I think it's not; there's a "minimum overhead" to living in the US that takes up a much larger fraction of $60477 than $1B, regardless of lifestyle. But people act like Bezos et al are just not paying as much as regular people, and it's just not true. $150M is more in absolute terms, and in many cases relative terms as well.
I'd like to see some (comprehensible to a layperson) discussion about what would happen if all income - wages, tips, gifts, inheritance, interest, dividends, capital gains, etc. etc. - was treated dollar for dollar equally from a tax perspective. I don't understand why it couldn't be, or why it shouldn't be.
There are also nasty effects with start-ups stocks or options that may be worth quite a lot of money but you may not be permitted or be heavily restricted in selling the stock even if you execute the options. There may still be a possibility of the stock going to zero leaving you with a large tax bill and no value in assets.
It is hard and not perfect, but we can't have everything based on income for high net worth people, they won't pay their fair share and keep getting richer and richer.
I think it's perfectly fine to only pay the tax once you sell, why should you keep paying a tax just for owning? With his portfolio, his salary wouldn't be able to cover a a simple 1% annual tax.
Now the issue is USA capital gain tax being lower than dividend tax, that's completely bonkers and encourages ridiculous uses of buybacks (which amazon has never done).
The capital gain tax should be the same as dividend tax