That said, my understanding is yes, if you know that the purpose of the travel is illegal, then you are aiding and abetting. If they can show it to a "preponderance of evidence" standard, they have the power (not "right") to seize your fare. If they can show it beyond a reasonable doubt, they have the power to punish you as well.
As rayiner mentioned previously, the preponderance of evidence standard is actually not terribly out of place here, being that disputes about ownership of property are generally settled that way.
And yes, it is something for a court to determine.
A hotel owned by someone who has no criminal record or charges is being seized because some of its guests have used it to commit their crimes.
Edit: Seems like the Judge ended up dismissing this specific attempt but the key to take away from this is that the government will try and also sometimes win such cases.
Well, to a degree. That was a bigger grab, since (at least as far as I can see in the article) they did not allege - much less demonstrate - that he had knowledge of any specific instances of criminal behavior.
In some circumstances, it's legitimate - "Yeah, I'll be getaway driver for your heist for $X..."
The allegation there was that he knew about these activities and was turning a blind eye to profit from it. And as you note, the government didn't win there.
That said, my understanding is yes, if you know that the purpose of the travel is illegal, then you are aiding and abetting. If they can show it to a "preponderance of evidence" standard, they have the power (not "right") to seize your fare. If they can show it beyond a reasonable doubt, they have the power to punish you as well.
As rayiner mentioned previously, the preponderance of evidence standard is actually not terribly out of place here, being that disputes about ownership of property are generally settled that way.
And yes, it is something for a court to determine.