License compliance is not a problem for open source users (opensource.com)

As it happens, Bruce Perens has asserted that he holds some sort of copyright over busybox, while the current maintainers deny that's the case. The fact seems to be that, today, there's no code in busybox on which Perens holds a clear copyright, or at least none on which a copyright statement with his name appears. Perens claims those notices were removed illegitimately, again, the current maintainers disagree. His assertion—one which he has not seen fit to have tested in court so far—seems to be something very close to exactly what I've described.

I have no comments on Mr. Perens' sanity or lack thereof—maybe you have some opinion in this regard—but, while we're on the subject, for someone who's questioning other people's sanity on no particularly clear basis (other than perhaps, pointless trolling), you're not establishing a very solid ground for your assessment.

While you're mulling that over, you might want to note that I'm not the person who called you a "hypocrite".

If you mean to ask when has a copyright owner in source code sued for non-literal copying, then there have been many cases. And they have won in some instances. And many more surely were settled after summary judgment was denied.

Lefty's opinions have a legal foundation, I just personally think he overstates things. But don't dismiss it as non-sense. It's rare that copyright cases turn on obvious, literal copying. Usually you get non-literal copying; i.e. copying certain abstract elements--such as arrangement--which elicit similar mental impressions. This is absolutely sufficient to infringe as a general matter if those impressions sufficiently relate to the protected "work". Note that in copyright when you write source code that source code isn't the "work" per se, rather it's the first copy of that work. Copyright protects the work which is in your head; and the protection commences the moment you fix that work into a tangible medium--i.e. create the first copy.

Most of copyright law turns on the breadth of protection for the abstract work. For computer programs that protected scope is narrower than, say, in the novella industry. Courts will find infringement of a subplot in a story more readily than it will several curiously similar subroutines in a program. If you want to know why, follow the Altai link I posted earlier (it's an anchored link to the relevant portion of the opinion); the court explains many of the most important reasons quite clearly.

The Alta opinion also cites many cases on non-literal source code infringement, albeit pre-1992. One would imagine that there have been substantially more cases since then, at least in the district courts. But copyright and patent software cases go all the way back to the 1960s, believe it or not.