I'm not sure I agree. Firstly, I bet that people have laundered plenty of money using online poker, and failed to report taxes on a lot of it, too. (Although obviously there's a difference in scale between a proposed new replacement currency and poker players' chips, and Bitcoin's anonymity makes it much easier.)
Secondly, what makes it much easier to evade taxes by failing to report Bitcoin payments than evade taxes by failing to report cash or check payments? Taxes work because enough companies and individuals pay them voluntarily that the cheaters can be cross-checked into oblivion. I don't see why people would be more likely to cheat if they were transacting in Bitcoin instead of cash.
Consider also the USG's attempts to enforce IP laws. Lots of sound and fury, but totally ineffective so far in actually curbing copyright infringement by individuals. And you know a lot of lobbyist money must be going towards trying to get those laws working. If people ever care about using Bitcoin as much as they care about downloading an album quickly and easily, then it seems to me that government is in trouble.
Secondly, what makes it much easier to evade taxes by failing to report Bitcoin payments than evade taxes by failing to report cash or check payments? Taxes work because enough companies and individuals pay them voluntarily that the cheaters can be cross-checked into oblivion. I don't see why people would be more likely to cheat if they were transacting in Bitcoin instead of cash.
Cash is pretty anonymous, but also pretty useless for paying people over the internet. Cheques typically leave an audit-friendly paper trail.
Tangential, but a subject of some local interest:
Why Bitcoin will fail by Avery Pennarun. "The sky isn't red." Thesis:
I'm not sure I buy these and am not competent to evaluate his claims on 3., but would like others' critique.
L019: Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen by Jason Calacanis. A rather more enthusiastic viewpoint of the project:
The actual text contains many more caveats than the eye-catching selection of points above.