No, he's disingenuously talking specifically about income tax, on interests.

Capital gains are on realized gains. Based on the difference between purchase price and selling price.

The thing is, wealthy people don't have interests bearing investments, because they don't need the cash right now. They either have unrealized gains (shares, real estate, etc), or interest bearing products wrapped in marked to market vehicules with reinvestment (ETFs, life insurance, mutual fund, etc).

Unrealized gains are not taxed as long as you don't sell them. If you need cash, you can borrow against them, so problem solved.

As for interest bearing investments, most companies nowadays use buybacks instead of dividends to avoid withholding taxes.