> Yes, that's true, but that not enough to enforce the tax code.
Uh, yes it is. Money came into your bank account, and you'll need to explain its origin if the IRS audits you.
Do you honestly believe the IRS would just give up on enforcing the law because you used a tumbler before you converted the bitcoins to USD and put the money in your bank account? The fact that you have the money in your account at the end of that process is what really matters.
In Canada I believe (don't own any bitcoin) you can withdraw from a few dedicated bitcoin ATM's, as far as I know you don't need to also use a regular bank ATM card in the process.
Yes, that's true, but that not enough to enforce the tax code. (See the update to my OP.)