Wrong. Instead of reducing the price the barman would take the $19 for himself and spend $1 on someone else's beer who also fits in the poorest group. That way the drinkers would get $80 worth of beer, paying $100 and the barman would gain popularity, because
he sponsors someone a beer everytime the guys come for a few drinks, and he'd also get a $19 bonus for his own expenses.
What everyone from outside the bar would know is that people who pay $100, get $100 worth of beer, and the barman spends
his money to buy a poor man a drink.
And so everyone would see that socialism is fair, and it helps the poor a lot more than capitalism (hell, the government spends
it's own money for them), and everyone begins to like it...
untill
they are affected by it and find out that there's
always someone poorer who gets more from the government, that it's
their money that the gov spends.
And the next thing they notice, is that the poor-people-loving government drives in comfortable Volgas, while the poor people ride a bus, and they have a little Fiat.
That's true socialism.
And so with a flat tax rate, everyone would get the same 20% discount on beer, proving pure and true capitalism works even better than the current system with the socialist "take from rich, give to poor" thinking.*
Therefore capitalism works better. Funny how the same example can be used to prove completely opposite statements...
* DISCLAIMER: Not that I do not support the idea of free beer, I just don't believe in the idea that someone who was slacking off at school, or is slacking off at work deserves to get one at the cost of those who work their @$$es off to make bigger cash.