The manual states that "At any point during operation the CarveWright machine can be stopped by pressing the STOP key or by lifting the cover." so people are going to use one of those two options. Considering if you accidently press the STOP key twice you will abort your project I think people tend to use the cover instead as I used to.

While there are several different opinions on how this cover safety mechanism works all agree that you should not rely on it functioning properly. That indicates a problem; a design issue, be it hardware or software, that should be addressed. Perhaps someone will take notice and look in to it.