I think we're getting a bit hung up on semantics. It happens all the time if you mean "accidental" in the sense that companies don't usually say "Hey! Screw the GPL! Let's pirate GPLed software!" The Software Freedom Law Center says:
"As we have worked to bring individual companies into compliance, we have encountered numerous violations resulting from preventable problems such as inadequate attention to licensing of upstream software, misconceptions about the GPL’s terms, and poor communication between software developers and their management."
On the other hand, if you mean "accidental" in the sense of some programmer saying "Honestly, I didn't mean to call that GPLed code. My finger must have slipped!" ... then I hope I don't have to point out that isn't realistic.
"As we have worked to bring individual companies into compliance, we have encountered numerous violations resulting from preventable problems such as inadequate attention to licensing of upstream software, misconceptions about the GPL’s terms, and poor communication between software developers and their management."
http://www.softwarefreedom.org/resources/2008/compliance-gui...
On the other hand, if you mean "accidental" in the sense of some programmer saying "Honestly, I didn't mean to call that GPLed code. My finger must have slipped!" ... then I hope I don't have to point out that isn't realistic.