Money from dividends, for example, are taxed at a lower rate than money from a job. A business owner who works in the company she or he founded would have to pay more self-employment payroll taxes compared to someone who merely had a passive interest in the same limited liability company who would pay only income taxes. In other words, the same income earned actively would be taxed at a higher rate than if it were earned passively.
As interest rates have been going down over the past 30 years, bond prices have continued to go up. With the 10-year yield (risk free rate) at roughly 2.55%, and the Fed Funds rate at 1.5% (two more 0.25% hikes are expected in 2018), it’s hard to see interest rates declining much further. That said, long term interest rates can stay low for a long time. Just look at Japanese interest rates, which are negative (inflation is higher than nominal interest rate).

Residual income is calculated as net income less a charge for the cost of capital. The charge is known as the equity charge and is calculated as the value of equity capital multiplied by the cost of equity or the required rate of return on equity. Given the opportunity cost of equity, a company can have positive net income but negative residual income.