Note that his system taxes capital gains, just as normal income.
Liberals believe the ideal system is where half of our citizenry pays no income taxes at all (or most likely, capital gains either) while a minority of taxpayers pays for all the services they enjoy.
This is what they consider "fair." In fact, most of them want the balance tilted even further.
Believe me, you wouldn't like a system that was actually fair. That is, where people paid pretty much their actual share of what they get.