I think the flaw in this reasoning is the statement "....this is technically a crime....".

I would have to see the actual law that your friend is referring to. I also wonder how many "laws" are still on the books that no prosecutor would even dream of trying to enforce. In Arizona, co-habitation of unmarried adults is technically a crime, as are many popular sex acts.

If any casino starts arresting folks who walk out with chips in their pocket, then I guess we can follow the trial and find out if this is a actually crime.

As far as eBay's culpability is concerned, I think the "no harm no foul" rule would come into effect.