Bryan,
Over here this system is called Prove-Test-Prove.
You have to prove that your tester is working properly first.
But, I was working with a Semi-retired Electrician recently, who got a shock when he locked out the wrong circuit.
He wouldn't listen to my rantings about safety and testing, he just said that he would be retiring in 3 years and didn't have time for new stuff.
I told him, he could be in a coffin tomorrow, and man did he hate that!!.