Probably the last man who knew how it worked had been tortured to death years before. Or as soon as it was installed. Killing the creator was a traditional method of patent protection.

He couldn’t see why people made such a fuss about people eating their silly old fruit anyway, but life would be a lot less fun if they didn’t. And there was never an apple, in Adam’s opinion, that wasn’t worth the trouble you got into for eating it.

They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance.

What's a philosopher?' said Brutha.
Someone who's bright enough to find a job with no heavy lifting,' said a voice in his head.

Don't you understand?" snarled Rincewind. "We are going over the Edge, godsdammit!"
"Can't we do anything about it?"
"No!"
"Then I can't see the sense in panicking," said Twoflower calmly.

And then Jack chopped down what was the world's last beanstalk, adding murder and ecological terrorism to the theft, enticement, and trespass charges already mentioned, and all the giant's children didn't have a daddy anymore. But he got away with it and lived happily ever after, without so much as a guilty twinge about what he had done...which proves that you can be excused for just about anything if you are a hero, because no one asks inconvenient questions.