Yeah. Would a reasonable person familiar with software think that there was no license agreement on the software? That's what would be litigated. "My client has only ever used GNU GPL software, he didn't know it was possible to sell software with terms and conditions imposed upon the end user." Maybe that's convincing, but probably not. That's why juries exist.

... only because you'd have no evidence of it. From a legal point of view, the question is what would come down if the judge were (somehow) convinced that it actually happened that way. Actually if a "perfect" judge were so convinced.

Probably a real judge would want to say something like "Why are all of you bozos in my courtroom wasting public money with some two-bit shrinkwrap bullshit? I was good at surfing. I could have gone pro. I hate my life..."