The wealthy already avoid many taxes. I don't think Bitcoin will make that much difference in tax avoidance. Taxes will still be collected on purchases at regular business and possibly when cashing out Bitcoin.
Wtf lol. Where do you live that doesn't have sales tax? This is about income tax. The government gets you coming and going. You made $30,000? I'll take 7. Now of that $23,000 you'll pay 13% tax on everything so it's really only worth ~$20,354. No wonder if rich people avoid taxes they get richer. Us poor bastards would save $10,000 a year!!!
I think he has sales tax in mind if he talk about purchases at regular business, so there is no way to avoid these. But this is still about income taxes like you pointed out. You have to pay those and as fore as i know the law states that you have to pay on your income. They does not specify in which currency the income is earned, so by using bitcoin you are not free of taxes. Just because it is harder to detect if you paid your taxes accordingly or not it does not mean that not paying is legal.