Things have changed over the decades. My grandfather was a master carpenter at the turn of the last century when it was not uncommon for carpenters to do the plumbing and electrical. His way of seeing if a circuit was hot was to wet his finger and stick the finger in a socket. I watched him check a new gas line (black pipe) by running a match along it after turning the gas.
The "good" ole days. Maybe this step was not done? -- Whoever said that ignorance is bliss wasn't refering to a person with a computer at his fingertips!